Chapter 4
Something in the Air: Specific Elements of Nature on the Brain
The fragrance with which one is feasted in the woods is, like music, derived from a thousand untraceable sources . . . the whole air vibrates with myriad voices blended that we cannot analyze. So also we breathe the fragrant violets, the rosiny pine and spicy fir, the rich, invigorating aroma of plushy bogs in which a thousand herbs are soaked . . .
—John Muir
Although it's clear, as the discussions in the previous chapters illustrate, that nature can provide benefit to psychological outlook and internal stress physiology, scientists are often inherently drawn to investigate at the microlevel. Simply viewing various nature scenes in an MRI scanner can capture the visual sense; yet, true nature immersion is an experience that can stimulate all of our senses. Scientists have not been content to simply accept the environmental link between visual nature and the workings of the brain; over the years they have dug deeper to determine whether specific elements of nature influence emotions and physiology. They have determined that beyond mere aesthetics and visual perceptions of beauty, nature can indeed stimulate the senses by way of specific variables, including plant-derived aromatic chemicals, natural light and colors, various sounds, and negatively charged molecules called negative ions.
As more and more people move toward an urban life, a greater understanding of how we can leverage some of nature's more potent elements, particularly as a way to buffer the stress of contemporary life, is a worthy scientific pursuit. It's not always so simple to escape the urban artificiality for a jaunt to the woods to get yourself that much-needed forest bath. A small dose of a specific element of nature may provide immediate calm and focus when stress and tension are rising. In putting together the scientific puzzle of our innate relationship to nature, the results of these more reductionistic investigations are underscoring the many ways in which we are intimately connected to countless minute aspects of the natural world.
In recent years, scientists have made stunning discoveries about the delivery of various drugs, including hormones, vaccines, and compounds with small peptide units, through the nasal route. They now recognize that the intranasal pathway is a potential route of entrance to the brain for a much wider variety of substances than once thought. Incredibly, nasally administered substances, including plant-derived vapors, are capable of entering the brain and then exiting into body-wide blood circulation.
Greenspace provides untold amounts of olfactory-provoking chemicals that appear to act synergistically, balancing mental outlook and facilitating effortless attention to the environment in which one is immersed. You can usually smell flowering plants, but even though a single tree of a single species can release several dozen aromatic chemicals, your sense of smell commonly fails to detect them. But just because they escape overt detection by your sense of smell does not mean they are without consequence to health. Collectively, these individual aromatic components are called phytoncide. Some of the individual components stimulate, while others sedate, so engaging in a forest bath (shinrin-yoku) exposes you to the entire constellation of aromatic chemicals, which can uplift and relax the brain. Experimental studies have shown that phytoncide produced from trees can lower the production of stress hormones, reduce anxiety, and increase pain threshold, while inhaling aromatic plant chemicals increases the antioxidant defense system in the human body. They have also shown an association between higher amounts of phytoncide in the air and improved immune function. Specifically, higher levels of airborne phytoncide cause increased production of anticancer proteins in the blood as well as higher levels of the frontline immune defenders called natural killer cells (NK cells). When we are exposed to viruses (e.g., influenza, common cold) and other infective agents, NK cells step up to protect us. Indeed, adults who have higher NK activity have lower frequency of colds. The work of physician Qing Li of Nippon Medical School in Tokyo has been groundbreaking. He has shown that on days when aromatic phytoncides (derived from Japanese Hinoki cypress trees) are aerosolized into hotel rooms, study participants have lower levels of stress hormones and increased NK activity versus control days. Business travelers and those traveling for an important interview or presentation can easily appreciate the significance of the findings. Furthermore, Li's team has shown that a weekend shinrin-yoku trip (walking one and a half miles twice per day) improves NK activity not only for a day or two; rather, compared with those walking in a pleasurable urban weekend control trip, the NK activity remained higher for an additional month. Even a day trip for forest bathing (in a suburban forest north of Tokyo) improved NK activity, with significant differences over baseline lasting for a week. Trees and plants secrete aromatic chemicals that impact our cognition, mental state, and even our immunity in ways we are only just beginning to understand. Isolating the individual aromas that aid with human wellness allows us to have more focused treatments with real-world significance to those beyond study participants. Here again, science is verifying something our ancient ancestors seemed to know well.
Airborne Aromatic Chemicals
For at least 4,000 years, aromatic plant extracts—wood- and flower-derived resins, gums, oils—have been prized and used for a wide variety of medicinal, religious, dietary, and ceremonial purposes. Ancient Greek physicians recognized that the aromas of certain plants tended to be stimulating, whereas the inhalation of other groups of plant-derived oils was reported to have a sedating effect. Ancients used airborne aromatic plant chemicals for ceremonial purposes to solidify the emotional connection felt by participants; the scents aroused the participants’ senses and enhanced their mental acuity and relaxation so they felt more fully present in the moment.
Although once lumped in with the stuff of crystal balls and black capes adorned with half moons and stars, aromatherapy and its application in human cognition and mental health disorders is now receiving increased interest from the scientific community. Large reviews of existing aromatherapy data show that in randomized controlled studies on anxiety and depression, subjects reported a meaningful reduction in symptoms, and the aromatherapy was safe and well tolerated. Experimental studies have shown that plant oil vapor can enhance the production of the brain's own calming chemical gamma-aminobutyric acid (GABA), while also boosting mood-regulating serotonin function.
Some of the more intriguing aromatherapy studies highlight the polarizing ways in which aromatic plant chemicals can influence the brain—some, such as rosemary and lemon oil, stimulate; others, such as lavender and rose oil, are more sedating. While walking through the forest can be both uplifting and relaxing thanks to the natural combination of plant aromas, aromatherapy offers an opportunity to fine-tune the advantages offered by selecting individual plant aromas. For example, a 2002 study conducted in the United Kingdom showed that workers toiling in cubicles scented with rosemary had significantly better memory recall than their colleagues who worked in unscented cubicles or cubicles scented with lavender. In fact, workers in the lavender-scented cubicles demonstrated diminished working memory and performed poorly on attention-based tasks compared with those working in unscented cubicles. So workers hoping to graduate from cubicle to corner office might do well to avoid lavender until after work, when they can use it to unwind.
Researchers at the Wheeling Jesuit University have conducted numerous studies in the realm of natural aromatic chemicals. They have reported that peppermint improves both physical and mental performance. When subjects inhaled very small amounts of peppermint, their typing speed and accuracy improved, as did their alphabetization performance. They also performed better on attention and memory-testing tasks and reported less fatigue than subjects who inhaled cinnamon or jasmine aromas or no scents at all. These same researchers also discovered that peppermint and cinnamon aromatherapy might just bring one back from the brink of road rage. In their experiment, the researchers found that prolonged driving led to increases in anger, fatigue, and perceptions of physical demand, as well as decreased vital energy. Peppermint and cinnamon decreased driver frustration and increased alertness; peppermint alone lowered the levels of anxiety related to extended driving. Interestingly, the aroma of fast food and pastries, both frequent companions on the road, aggravated drivers’ frustration and increased their willingness to speed.
In a study published in the International Journal of Psychophysiology in 2005, researchers at Coventry University, United Kingdom, found that jasmine may promote sleep quality and increase alertness the following day. During their three-night investigation, researchers exposed students to one of three conditions: jasmine scent, lavender scent, or no scent at all. Specifically, they infused the students’ rooms with the scent of lavender or jasmine at such low levels that many of the students were completely unaware of any scent at all. Not only did the jasmine sleepers toss and turn less frequently, they woke up feeling less anxiety. The jasmine sleepers also performed better on cognitive testing the next day. (Lavender was good too, but it couldn't match jasmine.) A recent study involving sophisticated brain imaging (fMRI) has reported that even without specific instructions to rate pleasantness and intensity, minute levels of jasmine aroma can enhance activity in the areas governing attention.
Research shows it takes only miniscule amounts of these aromatic chemicals to provide health benefits. Indeed, when it comes to aromatherapy, less appears to be more. For example, Japanese researchers reported that low levels of jasmine aroma can dampen down an overactive sympathetic nervous system—the stress branch of the nervous system. But those who told the researchers up front that they did not like jasmine had an increase in activity of that branch of the nervous system when exposed to high levels of jasmine scent.
Just as natural aromatic chemicals surround us in greenspace, human-made synthetic chemicals surround us in more urban areas, creating unnaturally polluted environments. And just as surely as miniscule levels of inhaled natural plant chemicals influence the brain, so too can synthetic chemicals. However, synthetic airborne chemicals and overt unpleasant odors typically have a negative influence on cognitive and emotional health. Exposure to indoor and outdoor airborne pollutants in residential and occupational settings has been linked to anxiety, depression, autism, aggression, irritability, pain, fatigue, frustration, short- and long-term cognitive decline, decreased altruism, and an overall downturn in individual helping behavior. Ambient air pollutants can set in motion a cascade of low-grade inflammation and have recently been linked to type 2 diabetes, cardiovascular disease, and obesity. Here, we are just referring to the obvious sources of outdoor air pollution from heavy industrial factories and traffic. Additional chemicals emitted from building material and the contents of buildings, including furniture, electronics, carpet, paint, cleaning supplies, vinyl flooring, faux wood, plastics, and air “fresheners,” also impact us negatively. Recent studies show that ambient air within indoor urban settings contains volatile chemicals, most notably benzene and formaldehyde, at levels that are beyond guidelines set by expert panels.
The computers in our homes and offices have been shown to contribute significantly to total indoor levels of toluene, 2-ethylhexanol, formaldehyde, styrene, and other potentially nasty chemicals. In a 2004 study, researchers at the Technical University of Denmark unpacked six new computers and operated them for 500 hours. Three weeks later they placed the computers behind a room divider. Otherwise healthy adults were randomly asked to perform cognitive tasks in identical workstations while unaware of either the presence or absence of the half dozen computers behind the divider. In the meantime, the researchers measured the air quality of the room while keeping air temperature, lighting, humidity, noise level, and air flow constant. The results of cognitive testing showed diminished performance and increased errors in those rotated through the workstations close to the hidden computers. The amount of volatile chemicals in the ambient air was significantly higher in the room with relatively new computers. The results confirmed a similar study where a decline in indoor air quality, due to a hidden chunk of polyamide-fiber carpet, diminished office performance in a series of randomized cognitive tests.
Here again, plants may come to the rescue, acting as a sort of vacuum cleaner for the air. While most people understand that plants and trees provide the oxygen we need, the role of nature as a cleanser tends to be underappreciated. In the late 1960s and early 1970s, researchers published several articles showing that certain trees and other plants (petunias, for example) were not only resilient against smog, they were able to significantly lower the levels of airborne environmental pollutants. Scientists such as Paul E. Waggoner made note of the great potential of plants, and trees in particular, as a way to purify polluted air in metropolitan settings. In the ensuing decades he has been proven right—plants are well capable of handling environmental chemicals, metabolizing and transporting them to the soil where subsequent bacterial action can render them less harmful. In the 1980s, a few years after environmental scientists established that various trees and plants could act as pollution solutions, and after they discovered some 107 nasty volatile chemicals within the air of their Skylab, NASA scientists stepped into the plant-air-purifying arena. The NASA group used the air-purifying properties of plants as a way to allow astronauts to remain healthy while working and living in enclosed spaces constructed of synthetic materials. Before the installation of the indoor potted plants, high levels of airborne volatile chemicals were emitted from the synthetic materials in the enclosed testing facilities, and sickness was frequently reported. Installing the plants quickly removed the volatile organic chemicals from the air and diminished the typical respiratory and eye irritation.
Since the first NASA reports, numerous studies published in scientific journals have shown that various plants can bring about a massive reduction in the amount of airborne volatile chemicals within offices and other enclosed spaces. Indeed, the potted plants involved in the investigations reduced indoor pollutants by 75 percent or more. Considering that urban dwellers spend 90 percent of their time indoors, these investigations have tremendous relevance to our health and well-being. However, this does not mean that we should be abusing plants and trees by using their absorptive strengths as an excuse to dump more synthetic chemicals into the air. Just because plants can soak up pollution for us—some 700,000-plus metric tons per year in the United States—it doesn't mean they should.
Depression—A Gray and Odorless World
When patients with depression are asked to pick out their favorite color, like healthy adults, they opt for a mid to light shade of blue. However, when looking at 38 color options, those with depression are far more likely to associate their current mood state with three shades of gray. Compared with healthy adults, twice as many individuals with depression equate their mood with a color. Those with depression aspire to see “the blues” while they suffer with grays.
A study published in 2010 in Biological Psychiatry explains why that might be—patients with depression have difficulty discerning the contrast between black and white: things literally look more gray, and the greater the severity of depression, the worse the difficulty with contrast. Add to this, research showing that patients with depression have smaller olfactory bulbs (which are responsible for smell) and a diminished capacity to detect minor scents in the air, and it becomes clear that those with depression perceive the world differently. Separate studies have linked impairments in the processing of smell and other sensory information to anxiety and ADHD. These findings underscore the need for additional nature therapy to treat depression. In fact, those with depression may have the greatest need for nature-based immersion—natural light, colors, and aromatic scents.
Light—Natural Deprivation and Artificial Gluttony
Timing is everything, the saying goes, and when it comes to the human relationship with the nonvisual aspects of light, this is especially true. There is much more to light than its essentiality in vision. Light hits the retina and sets off a cascade of biophysical events unrelated to vision. The interaction between environmental light and the light-sensitive cells in the retina is far-reaching and can ultimately influence sleep, alertness, mood, and cognitive performance. For some 2 million years, humans have been groomed on a steady supply of natural light from the sun, and the transition from morning light to evening darkness was the chief environmental signal for the brain's 24-hour cycle of arousal and sleep.
Natural light in the visible spectrum enhances cognitive performance during the day, and the withdrawal of light, in the transition from evening to darkness of night, brings about a decline in mental performance and an increased desire to sleep. The advent of electricity and the invention of the lightbulb gave us the option to extend the day and light up the skies. Burning the midnight oil became the rule for societies, rather than the exception. Today, more than half of the world's population lives under a night sky far brighter than nature allows for even with a full moon. While a full 20 percent of the urban workforce works at night, a much larger percentage are at home and technically off the clock, yet they too are illuminating their retinas as they “work” the screen. Modern computer monitors and plasma TVs can be very bright; in fact, flat-screen TVs can be 20-plus times brighter than a 60-watt bulb.
In contrast to our floodlit nights, we spend our daytime hours in environments that are often devoid of adequate natural light. Certainly, our use of artificial illumination can help to get us through our days, but we still don't get enough of the cognitively enhancing and mood-supporting visible light provided by nature. The typical indoor office cubicle provides a worker with artificial light some 100 times lower than midday winter sunlight. For workers confined to desks during the shorter days of winter, particularly at northern latitudes, this lack of natural light can contribute to melancholy. Our timing with light, it turns out, is quite the opposite of what it should be; we miss out on our daily fix of natural light, particularly during the winter months, and a few hours later we light up our eyes at a time when nature's darkness is telling us to wind down.
The connection between darkness and sleep, mediated via the hormone melatonin, is hard-wired within us. The production of melatonin is inhibited by light and enhanced by darkness. Production increases in the mid to late evening when the light begins to dim. Secretion and levels in the blood peak between 2 a.m. and 4 a.m.—some 20-fold higher than daytime levels. Studies have shown that it doesn't take much late evening or nighttime light to adversely affect melatonin production—flat-screen TVs and computer monitors boast about brightness, and their 400 to 1,000 lux can cause a sharp fall in normal melatonin production. Just 30 minutes of exposure to 400 lux illumination or two hours of 300 lux can significantly reduce nocturnal melatonin levels. You might be thinking that the 60-watt bulb used for reading is just as bad, or what about the oil lamp, the candle, and the hearth fire used by our ancestors? Not so much. These all produce illumination in the range of 20 to 60 lux and have very little effect on melatonin production.
There are massive consequences to the artificially brightened night sky. Recent experimental research shows that even low levels of light during the night can reduce brain plasticity and interfere with normal adult brain cell structures. And the health consequences, compounded by our interrupting the normal production of melatonin, include associations with insomnia, immune deficits, cancers (most notably breast cancer), obesity, daytime fatigue, attention deficit disorder, irritable bowel syndrome, fibromyalgia, and depression. Scientists are vigorously investigating the use of oral melatonin as a therapeutic agent in many of these conditions.
Light as Therapy
Why is it called “after dark” when it really is “after light”?
—George Carlin
Physicians have advocated purposeful exposure to natural light as a therapeutic intervention in mental health disorders for centuries. Two thousand years ago, Roman medical experts not only advocated therapeutic garden walks for those with mental illness, they also recommended that those with melancholy and chronic digestive problems live in spaces filled with light. In the early 20th century, clinical reports of improvement in mental health symptoms via exposure to the ultraviolet, infrared, and visible (light) portions of the electromagnetic spectrum began to accumulate. Hospital in-patient treatment plans widely discussed the use of southern-exposure windows to maximize natural light in patient rooms. However, despite the popular use of solariums, southern-facing windows, and machine-generated electromagnetic light therapy, there was little in the way of clear biological explanation for the beneficial outcomes.
It wasn't until the 1980s that researchers began to make consistent connections between low melatonin levels and depression. The early research focused on the use of bright-light therapy in those most sensitive to the shorter winter days—people with seasonal affective disorder (SAD). These early light therapy studies have since accumulated into volumes of international research clearly in favor of its value, and in 2002, Australian researchers confirmed sunlight plays a direct role in the production of the mood-regulating brain chemical serotonin, the very brain chemical drug companies have been attempting to elevate via Prozac and all of its chemical cousins. They found that the rate of serotonin production was directly related to the daily duration of ambient sunlight.
Now that researchers have determined that light therapy works to reduce SAD, they've turned their attention to additional considerations, including the appropriate dose and wavelength of light. Solar radiation arrives to earth as visible light, and the relatively slight variations in wavelength dictate the color that we actually see. The latest research suggests that the blue portion of the visible light spectrum, the very portion that shows the greatest relative decline in winter (compared with the longer wavelengths green and red), is most influential in mood states. The artificial light cast by traditional bulbs provides very little of the blue spectrum. Clinical intervention studies using blue-enriched white light or blue light (e.g., a goLITE BLU table-top and travel-portable light therapy box) suggest that mood symptoms can be improved without the hour or two required at 2,500 lux or the intense use of 10,000 lux with traditional units. For example, the goLITE BLU can provide results at 1,000 lux in as little as 15 minutes of exposure during the winter months. The gains produced by light therapy are not marginal: depression ratings have decreased by as much as 82 percent.
Given the broad therapeutic potential of oral melatonin and the mood benefits of bathing our brain cells in just a hint more serotonin, light therapy researchers have looked beyond SAD, examining other mental and cognitive health issues. Recent investigations have reported that light therapy is valuable in relieving other forms of depression, eating disorders, and anxiety. While SAD is relatively rare, occurring in 1 to 5 percent of the populations living at northern latitudes, a seasonal change in mood during the transition to winter is not uncommon. As many as one in two adults report a downgrade in mood and mental outlook when the dark winter days encroach and the clocks fall back. With hemispherical consistency, people type the word “depression” into the Google search box at far higher rates during the winter months. Looking at five years’ worth of global Google data over 54 geographic locations, researchers found that regardless of language, typing in the word “depression” and clicking on the Search button was dependent on season and latitude. During their summer, North Americans took a relative break from searching sites related to depression, while at precisely the same time, Australians were again back to the high level of depression queries. This underscores the notion that light deficiency might be its own syndrome, one that influences a greater portion of the population than that captured by the SAD diagnosis. It also suggests that light therapy, if provided at the right time and not via a flat-screen TV at 10 p.m., could benefit a significant group of people who sit just below the diagnostic criteria of SAD.
Light therapy (1,000 lux) in the morning can improve cognitive functioning, alertness, subjective happiness, low-grade anxiety, and subsequent sleep in otherwise healthy adults. More specifically, recent studies have again identified blue light as enhancing certain aspects of cognitive functioning over green, red, and violet portions of the spectrum. Studies using fMRI have shown that the blue portion of the light spectrum can specifically fire up areas of the brain that involve attention and memory. In a 2008 UK study conducted in the winter, blue-enriched white light was installed on one floor, while similar fluorescent tubes not enriched with blue were added on a different floor. Assessment four weeks later among 100 office employees revealed that the blue-enriched light improved mood, performance, alertness, irritability, and evening fatigue. The subjects on the blue-light-enriched floor also reported sleeping better at night, suggesting that they were keeping melatonin well suppressed during the day and taking advantage of daytime performance benefits without compromising sleep (such is not always the case with energy drinks and coffee). Unlike standard fluorescent tubes, blue-enriched fluorescent tubes provide the wavelength we need during the winter months, and thankfully they are now becoming more widely available (Phillips's Master TL5 ActiViva is one type).
The beneficial light used in the study was not merely blue; it was the full visible light spectrum enriched with blue, therefore it also included colors in the red and green ranges. Light completely devoid of red, orange, yellow, and green can influence brain functioning. Sophisticated brain imaging studies have shown that exposure to the green portion of visible light alone can deactivate certain areas of the brain. In 1903, Medical Age reported that select Russian prisoners were kept in rooms devoid of the red, orange, yellow, and green portions of the natural visible light spectrum. It was a form of torture without physical pain. After prolonged periods, the subjects were depressed and cognitively exhausted.
Blue Light and Suicide Prevention
In 1877, G.L. Ponza, director of a mental asylum in Alessandria, Italy, made international headlines when he reported preliminary work with colored lights and their influence on his patients. Canada Lancet stated that “the results attained by the use of blue and red lights were remarkable, the former quieting and soothing the patients into a calm condition, and the red exciting to violence.” In particular, blue light was said to produce its most profound effects in those with high levels of mental agitation.
Over a century and a quarter later, in 2009, executives from the East Japan Railway installed $200,000 worth of blue LED lights at select Tokyo train stations in an effort to curb suicides. Although no specific scientific research indicates that blue light can reduce suicides, contemporary studies do suggest that blue light can have immediate effects in brain cell communication, including those involving the emotion fear and fear-related behavior. Research shows that those who make violent suicide attempts have impaired decision-making processes in the brain. Blue light temporarily improves cognition and enhances responses to emotional stimuli, and brain imaging studies indicate that it can be an acute jolt to the system. For a despondent individual standing on the edge of the platform, the functional brain changes induced by blue light might be to the brain what defibrillation paddles are to the heart during cardiac arrest.
Why We Need Windows
Despite the wonderful advances in artificial light therapy, we cannot overlook the simple adjustment that requires no electricity: leveraging the value of simple windows. Indeed, not only do windows provide visual access to the outside world but they are the portal for therapeutic delivery of light from the sun. In the mid-1800s, it became clear that windows in the classroom, particularly south-facing windows, could play a role in the acceleration of academic progress. Writing in an 1869 issue of the Journal of Education for Ontario, school superintendent Newton Bateman stated that “neglect of the common principles of optics in providing and arranging light in school-houses is a common evil.” Even with the mass introduction of artificial light, natural light from windows was held in higher esteem for the educational environment, and up until the 1950s, schools relied on natural lighting to a large degree. Yet, in the late 1960s and 1970s, the tide turned, based on a short-sighted and erroneous view that windows were energy-wasteful. Skylights were covered up, buildings were retro-fitted with fluorescent bulbs, and designs became radically different. Windowless was the new trend.
Although glass might be back in vogue, the low natural light in many of these old school buildings remains, and the damaging effects persist. If we want our children to thrive in school, they need a view to nature and an access point for the sun to shine in. In recent years, windows in classrooms have been shown to enhance concentration, particularly during the winter months when children have less exposure to outdoor natural light. An investigation involving 21,000 students in three geographic locations (Seattle, Washington; Fort Collins, Colorado; Orange County, California) reported that students in classrooms with the largest window areas progressed as much as 15 percent faster in math and 23 percent faster in reading than students in classrooms with few windows.
The office is another environment in which windows are of critical importance. Workers in underground settings without windows have been found to be more anxious, hostile, and depressed than their colleagues on the windowed floors. Happiness is defined as having a preponderance of positive thoughts, and those working in windowless offices are more likely to experience negative thoughts in the course of the workday. As long as glare and temperature can be controlled, windows are highly prized by office employees; promotion to the corner office usually comes with financial compensation, more responsibility, and lots more natural light. Research indicates that employees sitting closer to windows are more content than their colleagues who sit closer to the core of a floor. Enhancing the level of daylight within interior workplace environments has been linked to improved productivity in a wide variety of industries. Of course, windows facilitate a certain view, be it of bricks or greenspace. People working in office settings would rather have a smaller window with a nice view than a large window with a not-so-nice view, yet any window is preferable to no windows in a workplace. While a view to nature can obviously enhance the mood and cognitive performance of employees, simply allowing sunshine into the interior space has been associated with increased job satisfaction, well-being, and intent to stay with an organization. Importantly, these latter findings were above and beyond illumination per se. In other words, it had nothing to do with brightness; it was letting some sunshine in that really mattered.
In health-care settings, windows provide a bridge to the outside world. In her nursing manuals, Florence Nightingale made specific references to the benefits of natural light and fresh air afforded by windows. She stated that there should be a maximum of two beds per window, and that patients should be elevated as much as possible so that they could see outside. She writes, “Window-blinds can always moderate the light of a light ward; but the gloom of a dark ward is irremediable.” Further, patients should “see out of a window from their beds, to see sky and sun-light.” Studies from 1996 and 2001 have shown that high levels of natural sunlight can expedite recovery and reduce the length of hospital stays in patients with either major depression or bipolar disorder. In patients treated after a heart attack, those who were assigned rooms with high amounts of natural light were more likely to recover faster, and amazingly, there was a 7 percent difference in mortality rates in favor of the rooms with high levels of natural light. Furthermore, in another chance finding, postoperative patients who had undergone spinal surgery reported less stress and lower pain levels, and used 22 percent less pain medication than post-op patients placed in rooms on the other side of the hospital—the side that happened to have 46 percent less natural light.
The benefits of windows are not exclusive to in-patient rooms: two studies have reported that even small windows in the intensive care unit are associated with less frequent delusions, hallucinations, and depersonalization post-recovery. Patients and hospital employees alike rank windows high on the list of desirable building features; of course, the view from those windows is also an important part of the equation. We have come a long way since Florence Nightingale's advice, and now bedside windows are often mandated by government regulations for hospital stays beyond one day. Indeed, large windows and rooms with a view to nature are now routine bragging points in hospital marketing literature.
Negative ions are charged molecules that we cannot feel, see, smell, or taste. The level of these molecules that we inhale is dependent on the environment that surrounds us. Negative ions are found in abundance in forests and near bodies of moving water. Negative ions in the air, molecules carrying an extra negative charge due to nature's splitting action, are yet another unseen and underappreciated aspect of outdoor natural settings. Researchers recently linked the regional abundance of negative air ions to improved human health and longevity. But negatively charged air ions, which are prevalent in natural settings, can become quickly depleted within polluted external environments, as well as in enclosed and air-conditioned rooms. Negative ions are also lowered by electronic devices found in homes and offices, such as computer screens, photocopy machines, and televisions. For example, the air in copy centers contains almost five times more positive ions than outdoor air on the same day.
According to research published in a 2004 edition of Indoor Air, negative air ions have been shown to promote our antioxidant defense system, lower blood lactate levels, and improve aerobic metabolism by enhancing blood flow. In an intriguing study published in the Canadian Journal of Anesthesia in 2004, a negative ion–generating machine was placed in a hospital setting where minor skin surgeries were conducted under local anesthesia. Unbeknownst to the patients, the machine was switched on or off during alternating weeks; humidity, temperature, and other background factors were controlled. Other than the local anesthesia, none of the 95 patients received medication. Psychological tests showed that those who had been exposed to the negative ions had less tension and a more rapid reduction in stress associated with the procedure.
Beyond the minor surgery study, various investigations have shown benefits of negative ions in reducing stress, depression, and anxiety, and improving cognitive performance. Research published in 2005 in the International Journal of Biometeorology shows that patients prone to panic attacks are much less likely to experience panic after a rainfall, when negative ion count is high. Researchers have been able to provoke anxiety, suspicion, and mania in environments with an absence of negative ions. Interestingly, the seasonality of ADHD, generalized anxiety disorder, depression, and panic disorder—all worse in the winter—may be to some degree influenced by the lower levels of negative ions found in the air during winter months. The föhn of Switzerland, Austria, and southern Germany and the chinook of Alberta have long been connected to irritability, headaches, and low-grade depression. These dry winds are distinct in their relative absence of negative ions. With the exception of post-rainfall, negative air ions are at their highest during clear, calm days with not too much or too little humidity. Since negative ions peak in the morning around sunrise and again during the late evening, walking in natural environments during these times could potentially be even more beneficial to your brain.
Jet Lag—Beyond Time Zones
Do you ever feel out of sorts after a flight? Most often this is, with good reason, blamed on jet lag; however, the aircraft cabin air itself may be a brain-changer. The humidity is very low inside aircraft cabins, the negative ion content is at low ebb, and ozone levels can be very high, sometimes double the World Health Organization's eight-hour guidelines. In a four-hour simulated flight, ozone levels comparable to what have been found on commercial flights (60 to 80 parts per billion) were associated with mental tension and more significant feelings of claustrophobia versus a low (less than 2 parts per million) ozone flight.
The underlying attraction of the movement of water and sand is biological. If we look more deeply we can see it as the basis of an abstract idea linking ourselves with the limitless mechanics of the universe.
—Sir Geoffrey Jellicoe
Much like green vegetation, water can play a direct role in our mood and cognitive restoration. Fresh water has always been required for our survival, and we have not been shy at taking advantage of the nutritional riches found in salt water environments. Various anthropologists have posited that the expansion of brain size and evolution of humans was driven by marine-derived fatty acids found in fish and shellfish.
Our attraction to water is evident. Both children and adults consistently rank water environments among their favorite places, and vacations and leisure activities often take place in aquatic environments. A water view can drive up real estate prices beyond the norm. When researchers at the United Kingdom's Plymouth University asked 40 adults to rate over 100 pictures of green natural and built urban environments, the respondents gave higher ratings for positive mood and preference to any photographic images containing water, regardless of environment (although greenspace, as expected, trumped the urban built environment). Interestingly, there was a consistent attraction to water up to a certain point—scenes containing between 33 and 66 percent water were, as Goldilocks would say, just right. Too much or too little water detracted from preference scores.
The healing powers of water have been promoted since Roman and Greek physicians used specific protocols to treat various ailments. In the late 1800s and early part of the 20th century, hydrotherapy became part of standard care for mental health disorders. In the 1920s and 1930s, hospitals featured specific hydrotherapy departments specializing in mental health care. Physicians used immersion in warm water or alternating hot and cold water, exposure to warm water vapor, warm and cold wraps (wet packs), and steady stream showers with varying degrees of success in treating depression, anxiety, fatigue, and mental exhaustion. In any case, with the advent of psychiatric drugs and talk therapy, hydrotherapy as a mental health modality was largely washed up by the mid-20th century.
Thankfully, a small group of contemporary researchers have tried to shed light on some of the physiological mechanisms whereby hydrotherapy might influence mental health and emotion. Immersion in warm water, it turns out, is akin to meditation in its influence on the central nervous system. Objective investigations have shown that warm-water bathing improves the balance between the branches of the nervous system governing stress and ultimately promotes activity of the “rest and digest” (parasympathetic) branch. The researchers have shown that the act of floating in warm water, so-called flotation therapy, reduces levels of the stress hormone cortisol, muscular tension, and cardiac rate, and improves emotional state. Objective testing has also shown that patients with anxiety disorders who were immersed in warm water experienced reduced muscular tension and improved symptoms of anxiety within about 15 minutes.
A series of recent Japanese studies indicated that warm-water bathing, bathing with added micro-bubbles of air, and the direct application of a mild stream of water over the legs and back while bathing all reduce physiological markers of stress and mental fatigue while improving mental outlook and cognitive performance. Separate Japanese investigators found that even warm footbaths could enhance sleep by improving stress-dampening branch (parasympathetic) activity. And combining airborne plant aromatic chemicals with water can enhance the effects. For example, lavender in a warm footbath maintains parasympathetic activity for a longer period than just a footbath alone.
In the attitude of silence the soul finds the path in a clearer light, and what is elusive and deceptive resolves itself into crystal clearness. Our life is a long and arduous quest after Truth.
—Mahatma Gandhi
Finding a remote spot in a natural setting can be an acoustical paradise. You might hear birds singing, creek water splashing on rocks, a twig breaking under hoof or paw of an animal, wind whistling through leaves or pine needles as trees sway . . . you get the idea. These sounds of nature are 180 degrees away from the sound waves emanating from a leaf blower, a jet aircraft, a helicopter, construction equipment, vehicle horns, and all the other artificial waves causing a modern-day acoustic smog in our urban and suburban environments. Noise is a plague, and although most of us know that high volume on our headphones or hanging out near a jackhammer can damage our hearing, the low-grade stress induced by noise-producing machines continues to be underappreciated. Environmental noise promotes the production of stress hormones, places a burden on the cardiovascular system, compromises cognitive and academic performance, depresses the immune system defense, contributes to insomnia, and enhances the likelihood of depressive thoughts and anxiety. Ultimately, environmental noise catches up with us: we now know that prolonged exposure to environmental noise can decrease longevity itself.
The imprint of 2 million years of nature contact on the contemporary human brain has been evidenced again as recent studies confirm that we detect and process nature-based sounds in different ways than we do modern sounds. One might presume that human-made alarm sounds—rapid-succession high-pitch sounds that provoke urgency—would lead to immediate attention in the contemporary brain. Yet, a study published in 2010 in the Journal of the Acoustical Society of America showed that natural sounds—from a lion, leopard, or jaguar, for example—produced faster reaction times than classical warning tones. On the other hand, natural sounds such as flowing water and birds chirping can mask the perception of road traffic and construction noises. The introduction of natural sounds turns down the annoyance factor of environmental noises. In office settings, nature sounds—wind, rain, stream water, ocean waves, birds—can mask steady machine noises, and employees prefer them over a setting without nature sounds. Hopefully, researchers will have a closer look to determine if this masking technique using natural sounds can put a dent in the harmful physiological effects of environmental noise.
Some studies have looked specifically at nature sounds as a means of lowering stress. In a 2010 study from Stockholm University, adult volunteers experienced brief mental stressors interspersed between sounds of road traffic noise or nature sounds (water and birds). A more rapid normalization of physiological markers occurred when the background noise involved nature sounds. In hospital settings, exposure to natural sound has been associated with better sleep in patients post cardiac surgery, lowered stress hormones during surgery, and pain reduction during bronchoscopy. The Japanese research team from Chiba University, shinrin-yoku experts Drs. Yoshifumi Miyazaki and Juyoung Lee, have shown that the sounds of a creek induce changes to brain blood flow indicative of a state of relaxation. The blood flow changes are in direct opposition to what is usually observed with mental stress and exhausting cognitive challenge. In addition, researchers have determined that listening to recorded bird sounds early in the morning can lift mood and decrease fatigue. In those with sleep difficulties, it also may help reset normal production of the sleep hormone melatonin.
National parks, forests, and wilderness areas remain our last bastion of noise refuge, and respondents en route to such areas often state that escaping from noise is a primary motivation for their visit. As interesting as the potential of natural sounds to mask urban noise might be, the converse is perhaps even more interesting: when machine noise comes to nature, the distress is amplified. Put simply, the annoyance factor when technological sound waves encroach into natural settings is very high. Machine-derived noise can quickly undo many of the positive attributes of nature discussed thus far. Nothing can dampen the restorative and mood-lifting influence of natural settings quite like the noise of a machine. Aircraft, traffic, chainsaws, landscaping equipment, motorboats, or motorcycles—all detract from positive perceptions of natural settings. In contrast, the sounds of nature, birds chirping, and water flowing enhance the positive mental outlook associated with nature scenes. Therefore, we cannot assume that all the previously discussed benefits of greenspace are due to green per se—the contextual acoustics might just make or break the mental benefit. Cities are expanding and acoustic energy is increasing—some cities have doubled their acoustic energy levels since 1990. Given that trees, particularly evergreens, provide superb insulation against noise, we should consider expansion of greenbelts and urban forests as one of the many steps we must take to limit our metropolitan noise problem.
Instant Mood Changer—Light, Sound, and a Chaser of Some Negative Ions
How rapidly can some of the natural elements we have discussed—bright light, sounds, and negative ions—influence mental outlook? Do these nature components, collectively known as environmental therapeutics, change mood in a rapid fashion? Research published in Psychological Medicine in 2006 suggests that using a light box (10,000 lux), a birdsong melody mix on CD, or a negative ion–generating machine can indeed facilitate mood change within 15 to 30 minutes, compared with a placebo, which was ineffective. These active components of nature reduced depressive thoughts and total mood disturbance among healthy college students at a meaningful level—a 41 percent average improvement from baseline mood, as well as reductions in anger. Obviously, such mood changes will only help to facilitate cognitive functioning and creativity. Hopefully, researchers will examine the effect of bright light, sound, and negative ions together in an effort to determine a synergistic effect.
For more on the use of negative ion generators and different light boxes, as well as self-assessment tools, visit the Center for Environmental Therapeutics website at www.cet.org.