I’ve loved the stars too fondly to be fearful of the night.
GALILEO GALILEI
HONORING THE SUN
PERHAPS NO OTHER NATURAL FORCE has a more powerful effect on all living things than the consistent rising and setting of the sun. It is the sun, after all, that rules over our circadian rhythm, our internal, approximately twenty-four-hour cycle of biochemical, physiological, and behavioral processes. Every living thing, from fungus to bacteria to plant to animal, has a circadian rhythm. As you approach your usual bedtime, your body anticipates what’s coming, and your bloodstream and brain reach their highest concentration of adenosine, a sleep-promoting neurotransmitter. Simultaneously, your body begins to kick out melatonin and reduce its core temperature, hitting its lowest point in the second half of your normal sleep schedule—around the time when melatonin will, incidentally, be at its highest. Your best sleep, not surprisingly, results from staying on course with your natural circadian rhythm.
For 2.5 million years of human history, and tens of millions of years before that, our genes have grown solidly, and inescapably, accustomed to the light and dark cycles of Earth. When we fail to obtain adequate sleep, we decrease our ability to process even moderate levels of oxidative stress. The impact leads to faster aging and measurable neurological decline. Our circadian rhythm governs our patterns of sleep, hunger, and wakefulness, as well as the flow of numerous hormones that support all aspects of health and wellbeing.
During sleep, elevated levels of testosterone, human growth hormone, and other adaptive hormones pulse through your body, a critical nighttime process that repairs organs and strengthens and rebuilds muscle. What’s more, your immune system’s white blood cells kick into high gear, with macrophages and leukocytes multiplying rapidly, thus inducing healthy flora to prevail over harmful bacteria. Your brain is also a beneficiary. The various phases of light-to-heavy sleep each night help your brain organize short- and long-term memories and fine-tune other cognitive processes like problem solving. Brain scientists call this synaptic homeostasis, but you might consider it a luxury spa makeover for the brain.
Just like a day at the spa refreshes your body, a night of sleep refreshes your synapses, the spaces located between nerve cells that allow the cells to communicate with each other. They respond to myriad, often overwhelming stimulation during your waking hours. The more enriched (or stimulating) your days are, the more your synapses grow, but they can only take so much before they exhaust. At the end of a busy day, when we say we’re “fried” or “drained,” we’re speaking literally. Under ideal conditions, you retire for the evening, and by morning, on cue with the rising of the sun, you awake naturally refreshed and rejuvenated, your synapses returned to their baseline values.
Of course, few of us these days enter our nightly slumber under ideal conditions. Stress, poor diet, sleep medications, cluttered sleeping environments, erratic bedtimes often disturb the delicate hormonal systems that restore the mind and body, to say nothing of excessive artificial light and digital stimulation after dark, when our circadian rhythm should signal us to wind down. Consider also the effects of air travel that unnaturally compresses or extends your days, and alarm clocks that force you awake. This is especially harmful before sunrise because it throws off your hardwired circadian-influenced hormone patterns.
A 2006 Harvard School of Public Health survey found that 75 percent of Americans suffer from some form of sleep difficulty, and a shocking 40 percent are seriously deficient, receiving less than five hours of sleep per night. By no small coincidence are the sleep deprived either suffering from, or are at increased risk for, numerous health problems, including hypertension, suppressed immune function, sexual dysfunction, thyroid dysfunction, premature aging, cancer, and heart disease. Mental health suffers, too. In addition to exhaustion, sleep deficiency is linked to aggression, depression, irritability, ADHD, and mood disturbance disorders. Even just a single night of deficient sleep can cause your level of cortisol to increase for prolonged periods of time, compromising your ability to handle the stress of a busy day.
Now let’s take a look at how the hormones and neurotransmitters that influence your circadian rhythm are supposed to work. Soon after it gets dark, melatonin levels rise—a hardwired process known as dim light melatonin onset (DLMO). When you feel drowsy, that’s your melatonin working its magic on you. Its job is to mellow you out by relaxing your brain waves and muscles while simultaneously lowering your body temperature, blood pressure, heart rate, and breathing rate. It’s also a powerful antioxidant, so it’s doing a fair share of cleaning house, too. Come morning, the rising sun triggers the suppression of this powerful hormone and increases the production of serotonin, a neurotransmitter that helps boost mood and energy levels during your waking hours. This, ladies and gentlemen, is your circadian rhythm at its best.
BASK IN THE WARM GLOW
For most of human history, nighttime meant darkness. I’m talking about real, permeating darkness. Camping darkness. Small-country-road-with-the-car-lights-out darkness. For our ancestors as recently as a couple hundred years ago, this kind of nighttime darkness lasted up to fourteen hours (well, it does today, too, but we mask it with lighting). Artificial lighting back then meant candles and firewood.
Today, in addition to artificial lighting, we possess computers, televisions, and digital gadgets that emit blue light, named for the sustained and vivid hue on the electromagnetic spectrum, which runs from infrared to ultraviolet. The bluer the light, the more intense it registers on the Kelvin temperature scale. For reference, candle light, which falls in the red-orange-yellow area of the spectrum, burns at 1800K; incandescent indoor light registers around 3000K; ultraviolet noon sunlight comes in at 5500K; and the light emitted from most computer monitors registers a whopping 6500K!
Apologies to Thomas Edison, Steve Jobs, Bill Gates, and the rest, but they did play a role in thrusting us violently—genetically speaking—into the Digital Age. Exposure to artificial light after dark suppresses melatonin’s DLMO effect and triggers instead an elevation of cortisol and other stress hormones. So, why should this concern you? Because this unnatural spike in cortisol not only keeps you from falling asleep, but also causes sugar cravings, elevates ghrelin secretion (which stimulates hunger), elevates insulin levels (which promotes fat storage while you sleep), and compromises the effects of leptin, an important hormone that regulates appetite and fat metabolism hormone. Translation: Blast your retinas with artificial light, and you’ll get the late-night munchies. And you’ll signal your genes to store these calories as body fat.
The synergy of light, appetite, and fat storage is actually a desirable evolutionary process kicking in. Our ancestors stayed up later in the summers eating carbs in the form of seasonal fruits, vegetables, and tubers. This triggered hormonal processes that prompted their bodies to start storing fat, a desired effect when considering the long, cold, dark winters that lay ahead. Bear in mind, these were times when winter meant zero carb availability, meaning, instead of burning stored glycogen and muscle in the winter, our ancestors burned mostly fat. Most people today, however, are locked into a fat storage pattern year-round, thanks to a high-sugar, grain-based diet and artificially lengthened “days.”
Over a lifetime, excessive exposure to blue light can result in a variety of degenerative eye diseases, including cataracts and macular degeneration. Furthermore, researchers believe that a lifetime of excessive light exposure (and the related suppression of melatonin) is harmful not just to your eyes and sleep cycles, but can also increase the risk of many forms of cancer.
To that end, your best bet is to make a sincere effort to get by with the absolute minimum amount of artificial light possible when indoors—even during the day. This will help ease eye fatigue and potential long-term damage from excessive blue-light exposure. Don’t be afraid of actual sunlight, however. Just as it did for Grok, sunlight ignites serotonin production and delivers vitamin D, which, as we’ll discuss shortly, plays a critical role in healthy metabolic, cardiac, immune, skeletal, and neurological function.
So, as the sun begins to set, that’s your cue to minimize your light exposure, especially blue light. Hey, it isn’t that bad. Low-temperature light—such as that found in fire flame—has no effect on melatonin production and facilitates relaxation of the central nervous system even more than lowering general ambient light. This makes romantic candlelit evenings a great way to stay aligned with your circadian rhythm. Grok really knew what he was doing when he built his campfires!
For those nights when it simply isn’t practical to live by the light of fire, consider purchasing yellow-, orange-, or red-tinted light bulbs (often marketed as “bug bulbs” at home supply stores), and switch out lamps in your home as you see fit to afford low-light evenings. Another effective strategy, particularly if you are working or watching computer and television screens after dark, is to wear yellow- or orange-tinted glasses with UV protection. Light-colored lenses let sufficient light in so you can see fine, but, with the familiar UV designation (indicating protection from the sun’s ultraviolet rays), they protect you from the damaging effects that indoor blue light has on your melatonin release. You can purchase a quality pair of yellow- or orange-tinted sport lenses from leading sunglass manufacturers such as Smith Sport USA, or acquire inexpensive safety glasses of similar colors from a big-box home-supply store or Internet resources.
SWEET DREAMS ARE MADE OF THESE
Your bedroom should be considered a sanctuary devoted to sleep, relaxation, and intimacy. TVs, computers, clutter, including stacks of mail, piles of laundry, and old magazines, have no place here. Even your smart phone is off limits, unless perhaps you’re using an app to play soothing nature sounds. Add plenty of plants to purify the air. Maybe even a few candles—that’s a nice touch, too. You want your sleeping environment to be warm and inviting; however, when it comes to the actual temperature, you definitely want to lean toward the cool side. Evolution has programmed us to sleep in environments that are cooler by night than they are by day. Bundle up under the covers, but keep your head in cooler-than-daylight temperatures. Research suggests that the optimal room temperature for sleeping lies somewhere between 60 and 68 degrees Fahrenheit (16 to 20 Celsius), so set your thermostat accordingly. Or go truly Primal by cracking open a window and letting the fresh, cool air drift you off to sleep.
As for bedding, our ancestors likely made the best of soft sand, piles of leaves, or even just the bare ground. While some Primal enthusiasts tout the benefits of firm sleeping surfaces, personal preference should guide you to the most comfortable bedding and pillow setup. Spend some time experimenting with different options and splurge for the best—after all, you (hopefully) spend a third of your life in bed! Since back and neck pain are so common these days, it’s important to observe correct sleeping positions, as detailed in the sidebar for the Gokhale Method for Lying Down (see page 146).
When it’s time for lights out, your sleeping environment should be completely dark. Do whatever it takes here. Install blackout curtains or room-darkening blinds. If light streams in through cracks of your windows, cover them with heavy dark fabric or paper. Shield LCD readouts, wedge a towel under the door to block interference from other rooms, and keep a flashlight handy instead of plugged-in nightlights. Use a sleep mask when you sleep or nap during times when it’s not dark outside, or when you can’t completely darken the room for whatever reason. Yes, this is a huge deal, even if you claim to be an easygoing sleeper.
Research has shown that it’s not just your eyes that are light sensitive, but the entire surface of your skin as well. Even a single beam of light hitting the back of your knee has been demonstrated to disrupt melatonin levels and upset your circadian rhythm. Consequently, once your body fully acclimates to sleeping and waking with the cycle of the sun, even the most aggressive blackout effort probably won’t stop you from gracefully waking at the break of dawn. For one, lighter sleeping cycles predominate in the morning. And secondly, environmental cues called zeitgebers—German for “time giver”—typically stir you out of sleep. These cues also help sync your circadian rhythm, and in addition to daylight, include warming temperatures and the sounds of nature such as chirping birds.
THE HOURS OF THE NIGHT
Although it might feel like it some days, hitting the pillow doesn’t mean an instantaneous plunge into cataleptic nothingness. Sleep follows a progressive spectrum of sorts. We likely all recall the REM (Rapid Eye Movement) and non-REM designations from our middle school health classes. The picture is a bit more complicated than that, but those categories represent the bones of it. Essentially, the body moves through three stages of non-REM sleep called N1, N2, and N3, proceeding eventually to REM sleep, characterized by dreaming. The typical pattern we follow is N1, N2, N3, N2, and then REM. A complete cycle through this pattern lasts about ninety minutes, and the cycle repeats several times throughout the night. Early in the evening, your N3 deep-sleep cycles are prolonged, and your N1 and REM sleep cycles are relatively short. As you progress toward awakening in the morning, your deep sleep cycles are shorter and your lighter sleep cycles lengthen—making it easier to awaken refreshed and energized after a complete cycling through all the necessary phases or restoration.
Phase N1 represents the initial switch in brain-wave frequency. It’s the stage in which you feel like you’re mostly under but can still sense the presence of the exterior world. It characterizes most surreptitious office naps that people think no one will notice—until your head slips off the hand that was holding it up. It’s the stage in which you scare yourself (and your sleeping partner) with those annoying sudden jerks. From there, N2 takes you down enough that any residual awareness of your environment is gone. We spend about 50 percent of our sleep in this stage throughout the night. During this stage, we consolidate the learning of complex motor skills and upload information processed during REM sleep into long-term memory. Those hours of piano practice or shooting three-pointers get hardwired into your nervous system circuitry. The process, known as long-term potentiation (LTP), becomes, as the complexity of the learning increases, more dependent on good sleep. So, when NBA players and concert saxophonists take their customary naps before evening performances, they are getting a potentiation boost for the complex motor skills they must master.
Finally, at N3 you reach deep, slow-wave sleep. This is where we spend about 30 percent of our total sleep time. Adaptive hormones flow at peak levels, and macronutrients are synthesized efficiently so that your bones, muscles, and organs are repaired and replenished. Slowed brain function at this stage helps clear your mind of unnecessary clutter and insignificant memories. Since slow-wave sleep predominates early in your sleeping period, it’s critical to get to bed on time. As an old sleep proverb states, “An hour before midnight is worth two after.” Keep that in mind next time you’re tempted to stay up for just a few more emails or a late-night talk show.
We spend about 20 percent of our sleeping hours in REM. In this state, your muscles are paralyzed to keep you from acting out your dreams while your racing mind consolidates and processes information from your day for storage into long-term memory. REM sleep helps to improve spatial, perceptual, and visual skills, as well as sort out emotional experiences and stressful events, improve neural connections that strengthen memory, and replenish important mood and cognitive-boosting neurotransmitters like serotonin and dopamine.
“REM sleep helps to improve spatial, perceptual, and visual skills.”
While it’s nice to achieve the tidy, repeating pattern of N cycles into REM cycles, don’t be alarmed should you spin out of a sleep cycle sometime during the night. Researchers believe that our primal ancestors likely engaged in biphasic or possibly even polyphasic sleeping habits instead of sleeping in one uninterrupted stretch as most of us do (or try to do) today. Their night’s sleep was likely interrupted to tend to the fire, feed and care for infants, or keep watch for danger.
According to historian A. Roger Ekirch, the author of At Day’s Close: Night in Times Past, segmented sleep predominated up until the Industrial Revolution. Ekirch’s groundbreaking research, validated by more than five hundred references in historical documents, suggests that we have a natural preference for polyphasic sleep and that many modern sleep problems stem from overriding this preference with too much artificial light after dark. As a result, we retire for the evening much later than we would otherwise, and try to make up the time by sleeping in one interrupted stretch throughout the night.
According to Ekirch, after catching a few hours of quality shut-eye, people before the Industrial Age would naturally stir out of sleep in the middle of the night and engage in assorted activities such as sex, prayer, writing, interpreting dreams, visiting neighbors, and smoking tobacco. The unscrupulous engaged in petty crime, but most generally enjoyed the nocturnal free time that was, for the working class, virtually nonexistent during the day. This wakeful segment lasted one to two hours, followed by another good chunk of sleep lasting till sunrise.
Ekirch and other sleep scientists believe there are numerous health benefits from segmented sleep. Studies show increased levels of the hormone prolactin during periods of late-night wakefulness. While commonly associated with lactation, prolactin provides hundreds of other benefits, including regulating immune and endocrine functions, and promoting gratification and relaxation after sex (countering the arousing effects of dopamine that occur before sex).
The idea that we are programmed for biphasic or polyphasic sleep is not a new one. In 1992, the National Institute of Mental Health conducted an experiment that involved depriving a group of sleep subjects of light for weeks at a time, causing the subjects to fall into a segmented sleep routine very similar to that described in Ekirch’s historical diaries, court documents, medical books, and literature.
Segmented sleep should not be confused with the common condition of sleep maintenance insomnia, which occurs when people awaken in the middle of the night and have difficulty falling back asleep. In fact, findings suggest waking up regularly in the night might not constitute the sleep disorder it’s commonly made out to be. In other words, it may be natural—and not all bad. Just don’t turn on any blue lights that could suppress your evening melatonin.
If you have to get up and move around, replace your plug-in nightlights with a small flashlight at your bedside, and, if your want to be ultra diligent, tape it with some red cellophane over the lens to stay within the warm-light range. Or wear yellow-orange lenses and use a low-light, lightweight headlamp, essentially a strap-on “miner’s light,” or use a specially designed book light. Yes, I admit the miner’s light is quirky. But it works, and it’s great for mellowing out the kids at bedtime. You can pick up an inexpensive one from a hardware store or check out one of the fancy models from the Petzl brand. But do whatever it takes to get cozy and minimize light as much as possible during these mid-night awakenings. And as soon as you feel drowsy, just shut things down and return to sleep.
Regarding the optimal amount of sleep you should get, genetics as well as your levels of activity, stress, fatigue, and general mental and physical health all influence what your magic number is. While conventional wisdom’s eight-hour recommendation is reasonable and safe, an often overlooked element of optimal sleep is the need to vary your sleeping habits in accordance with the seasonal sunlight exposure at your latitude.
In the book Lights Out: Sleep, Sugar, and Survival, authors T.S. Wiley and Bent Formby make a strong case for getting 9.5 hours per night for six to seven months of the year, and eight or less during the longer days of summer. Those living in the tropics require less variation, while those living near the polar regions need more variation between summer and winter sleep patterns.
Granted, 9.5 hours might seem excessive considering the hectic twenty-four-hour cycles we push through today. But consider this: when you honor this connection, you are more productive and focused during the peak hours of the day. You get more done faster, easier, better, more creatively. Set a Primal Connection priority of winding things down after dark with just a bare minimum of lighting and little, if any, digital stimulation. Enjoy quiet, calming activities instead such as neighborhood strolls, conversation, reading, or board games with the family. Mellow, low-light evenings should adequately induce the effects of DLMO to get you settled into sleep soon after dark. For those in the continental USA or living at similar latitudes, a good time to go to sleep is somewhere within one to two hours of sunset during the summer months and within four to five hours during the winter months.
GOOD MORNING, SUNSHINE!
As we have just learned, your body’s biological clock, better known in the scientific community as the suprachiasmatic nucleus (SCN), gently tucks you in to sleep at night with melatonin, and awakens you refreshed the next morning with serotonin. If you are strongly aligned with your circadian rhythm, your morning hormonal process works by first receiving light through your retina. From there, a signal travels along the optic nerve to your SCN and swiftly sends signals to other regions of your brain, including the pineal gland, which activates the release of serotonin. This high-energy neurotransmitter makes you feel alert and happy, and helps you learn and process memory. Not enough of it and you suffer, namely from depression. Levels of the stress hormone cortisol begin to increase within the first thirty minutes of your awakening as well. While cortisol is often maligned as health-compromising when produced in excess, this morning bump is a desirable genetic mechanism that prepares you for the energy demands of a busy day. In fact, the serotonin-cortisol effect is most pronounced when you awake close to sunrise, so early risers have an added advantage.
If waking up naturally on schedule in the morning is difficult for you, try moving your bed near a window that receives sunlight. This is a good option if you can keep your room decently dark during the night. If the environmental cues of chirping birds, trickling water, or ocean waves are a lacking feature near your home, research suggests that nature sounds produced by a variety of sophisticated alarm clocks and cell phone apps might help. Some models emit a gradually increasing glow a half an hour or so before your scheduled wake-up time, and others provide your choice of soft ambient sound. Guaranteed, you’ll awake more gracefully using this hack than by the artificial and disruptive noise of a traditional alarm. Such rude awakenings stimulate an undesirable spike of stress hormones, in contrast to the optimal elevation caused by sunlight. You want to wake refreshed, not in a state of fight or flight.
SLEEP AND WAKE HACKS
Sometimes you need to manipulate the cycle of your circadian rhythm to your benefit, particularly if you are among the many folks—shift workers, parents caring for infants, and so on—who routinely require sleep during daylight hours.
Sleep masks. Also known as blindfolds, this sleeping solution creates a dark environment anytime you want to induce or prolong sleep. Check with your local drug store or DreamEssentials.com.
Noise-canceling machines. Fans, air purifiers, digital nature sounds from your music device, or noise-canceling machines counter potentially disruptive, narrow-frequency external noise such as barking dogs, a snoring partner, and loud voices that can interfere with sleep.
Power naps. A natural, circadian-influenced energy lull happens about seven to eight hours after you wake. Assuming you wake near sunrise, by early afternoon you may on certain days experience a dip in energy. During this lull, your body temperature drops to its lowest point during daylight hours, making early afternoon an ideal naptime. Don’t be dissuaded by the common sentiment that napping will throw off your evening sleep. No research supports this, and in fact some research suggests otherwise, that a well-timed twenty-minute catnap (or even a big-time nap of up to ninety minutes) can actually improve your evening sleep, even if you suffer from insomnia.
Light therapy boxes. We’ve talked about minimizing light, but if you live in a sun-challenged environment, have a work schedule that is at odds with the sun, or suffer from seasonal mood disorders, consider a light therapy box that mimics ultraviolet daylight and can help you regulate your circadian rhythm. Brief exposure to a light box when you wake can stimulate the production of serotonin and other awakening hormones. Purchase a high-quality unit with a certifiable output level of around 10,000 lux and an effective UV filter to ensure safety.
Tanning beds. Another way to work around seasonal mood disorders. Be careful not to go overboard and chase the high with this hack. Consider brief exposure only, about twenty minutes a week. Make absolutely sure you patronize a facility that uses the latest technology; that is, low- or medium-pressure lamps that emit a balance of UVA and UVB radiation similar to sunlight. Ask your salon about these sorts of lamps. If they don’t know what you’re taking about, choose another salon! I strongly recommend covering your face with a towel while you fake bake, since our faces get plenty of sun exposure and are most susceptible to wrinkling and carcinoma over a lifetime. At the very least, protect your lips and wear goggles over your eyes.
F.lux. If you must work on your computer after sunset, take regular screen breaks to rest your eyes and brain. And don’t forget to use your yellow-tinted sunglasses to cut down the blue-light exposure! Downloading F.lux (Stereopsis.com), a free computer program that works by warming the color temperature of your computer display to a more mellow pink-colored hue after the sun sets in your area, is another great option for late-night writing jags.
VITAMIN D AND THE SUNNY SIDE OF LIFE
No discussion of the rising and setting of the sun would be complete without acknowledging the powerful impact direct sunlight has on the production of vitamin D, which, as previously stated, is technically not a vitamin but another potent and essential hormone. Within your epidermis, enzymatic “biofactories” convert cholesterol derivatives to vitamin D when UVB rays of sunlight hit your bare skin. (Yes, cholesterol! Like sunlight, our bodies would not be able to function without it.) The newly created vitamin D is then distributed to receptors located within cells throughout your body, playing a central role in metabolizing calcium; strengthening immunity, cardiac, and neurological function; and, ultimately, gene expression.
Overall, some two thousand genes are influenced—or turned on—by vitamin D, triggering elevated levels of beta-endorphins and serotonin. We’re talking about some serious feel-good stuff here! Vitamin D also works to regulate cell growth and renewal, particularly by acting on the P53 gene, the appropriately named “DNA proofreader” gene, which is responsible for overseeing hundreds of millions of daily cell replications. It’s also involved in apoptosis, the natural self-destruction of superfluous or damaged cells before they become malignant. In the absence of vitamin D, however, the P53 gene will down-regulate—or turn off—and the risk of many forms of cancer, including melanoma, will dramatically increase.
Without question, the sun has left a deep imprint on our genetic makeup and primary biological processes, dating back some 350 million years, when vertebrates first left the calcium-rich sea for land. Vitamin D synthesis set the stage for creatures to proliferate and become more complex with healthy, mineralized skeletons. Evolutionary biologists report that vitamin D’s ability to boost immune function and destroy invading organisms has been conserved in the genome of all primates for over 60 million years.
So, it’s pretty darn clear that receiving adequate vitamin D is an essential component of being a healthy, happy Homo sap sap. And yet a 2009 study published in the Archives of Internal Medicine reveals that 77 percent of Americans have insufficient levels of it in their bodies. In fact, we’re learning that vitamin D deficiency is one of the most disastrous disconnects in modern society. How did this happen? How is it that in the beginning of the twenty-first century, in developed countries, we are seeing a resurgence of all sorts of debilitating health problems, including a rise in cancer and a return of rickets?
“vitamin D’s ability to boost immune function and destroy invading organisms has been conserved in the genome of all primates for over 60 million years.”
Our sedentary indoor lifestyle is one big reason. And when we do go outdoors, flawed conventional wisdom encourages us to shun the sun, and cover up and slather sunscreen all over our bods, from head to toe. We’re warned of wrinkles and skin cancers with ominous names like malignant melanoma and basal cell carcinoma. But the reality is no scientific evidence links regular, moderate sun exposure to any form of skin cancer. Only excessive sun exposure presents a skin cancer risk, and even then mainly for carcinoma—the easily treatable condition—and not melanoma, the far more serious condition.
For every skin cancer diagnosis attributed to excessive sun exposure, there are fifty-five more cancer diagnoses attributed to insufficient sunlight. University of California researchers believe that more than sixty thousand annual cases of colon and breast cancer worldwide can be prevented simply by increasing the intake of vitamin D.1 In fact, recent studies link vitamin D deficiency as the root cause of other health complaints such as depression, fibromyalgia, and muscle and joint pain. Think about that the next time you layer on a thick glob of sunscreen. One with a Sun Protection Factor (SPF) of 8 compromises vitamin D by 90 percent, while SPF 30 blocks 99 percent of vitamin D. (Never mind that a good Primal Blueprint diet and, guess what, adequate vitamin D, bolsters our natural sunburn and sun damage defenses.)
Obviously, sun exposure is all about striking the right balance. Too little or too much, and you pay the consequences. So, how much is enough? And what’s the sensible approach?
The darker the natural coloring of your skin, hair, and eyes, the more melanin pigment you possess. Melanin is a natural chemical in your body that protects your skin from excess solar radiation (UVA ultraviolet light), so the more you have, the more you can enjoy risk-free sun time. Those with red hair and extremely fair skin have difficultly manufacturing melanin. If you have fair-to-medium skin pigment, you can easily synthesize vitamin D, but you burn easily. Strive for a slight in-season tan—somewhere between ten to twenty minutes of direct sunlight daily over 25 to 50 percent of your body. Avoid burning, and you will be safe. But even at the equator, the early morning and late afternoon sun is not intense enough to support vitamin D production, so your window of opportunity typically lies between 10 a.m. to 3 p.m. only during the periods of mid-spring to mid-autumn in the latitudes where most North Americans and Europeans live. A good in-season strategy, represented by that slight tan, should keep enough vitamin D cycling through your system year-round. This is because your fat cells store enough vitamin D to get you through the winter months.
The darker your eyes and skin, the more time you need to spend in the sun to manufacture optimal amounts of vitamin D. This has become a serious complication for those of African descent living indoor-dominant lifestyles outside the tropics. Recent findings show that African American males have an 89 percent greater risk of cancer mortality than white men, and have particularly high rates of digestive tract cancers (colon, rectum, mouth, esophagus, stomach, and pancreas) that are strongly linked to vitamin D deficiency.
DIALING IN YOUR VITAMIN D STRATEGY
Manufacturing vitamin D from sunlight occurs only when ultraviolet radiation is greater than 3 on the UV index, something that is affected by numerous variables: high altitudes (the more intense the UV, the more vitamin D production), reflectiveness of ground surface (light reflected off sand, snow, concrete and water increases vitamin D production; the opposite for grass and other less reflective surfaces), pollution (minimizes UV, and therefore lessens vitamin D production) and obviously time of day, time of year, and your skin pigment. Since “maintain a slight tan” might be too vague of a recommendation for something this critical to your health, it’s helpful to have a basic understanding of how to optimize your vitamin D production, predominantly through sun exposure.
Dr. Michael Holick, author of The Vitamin D Solution and one of the world’s leading authorities on vitamin D health, recommends a maximum safe sun exposure time of half the amount of time it takes to sustain a slight (pink) sunburn that is noticeable twenty-four hours later. This benchmark—which Dr. Holick refers to as one minimal erythemal dose (1 MED) automatically factors in all the aforementioned variables. For example, a redhead on a white-sand beach in Southern California in mid-summer can burn his or her skin in a matter of minutes. Someone of medium skin pigment playing on a grass field in New York City in the fall, however, can spend a couple hours in the direct sunlight without burning.
If you obtain sun exposure equivalent to half of 1 MED (half of burn time) over approximately half of your skin surface, your body will produce an estimated 2,000 to 4,000 International Units (I.U.) of sun-obtained vitamin D, which, incidentally, lasts twice as long in your body as a vitamin D supplement of the same amount. Knowing this, it becomes clear how insignificant dietary vitamin D sources are, and how important it is to expose large skin surface areas of your body to sunlight frequently during the months of peak solar intensity at your latitude. Naturally, your half a MED exposure time will be an estimate, since there is no reason to sustain a burn in order to pinpoint your 1 MED time!
By the way, if you are imagining your dermatologist cringing at the suggestion to expose your fair skin to more rays, go ahead and cover sunscreen on your face, neck, and hands whenever you spend time in the sun. Protecting these vulnerable areas from potential wrinkling and cancerous growths will not materially hamper your body from manufacturing vitamin D. This is because your face and hands represent only a small fraction of your total skin surface and total vitamin D manufacturing potential. Focus on your legs (36 percent of total skin surface), back (18 percent), abdomen and chest (18 percent), and arms (18 percent) for vitamin D production, since they have far less risk of chronic exposure damage and loads of potential for vitamin D production.
Still, for a variety of reasons, many of us find it a challenge to expose large areas of our bodies to the sun at midday. For example, you may live at a latitude that is incongruent with our skin pigment and ancestral heritage. Or you may find the sun’s rays in your area are only intense enough to make vitamin D for a portion of the year. In such cases, supplementing with vitamin D can be extremely useful to ensure that you maintain healthy blood levels of the nutrient year-round. A typical small capsule might dispense 2,000 I.U. And, since vitamin D can be easily stored in your skin, you can take several pills at a time and not have to worry about regimented daily pill popping. In the winter months when UV intensity is low, I recommend getting an average of 2,000 I.U. of vitamin D per day.
“Conventional wisdom has long touted a good old glass of milk for a vitamin D boost, yet it delivers a mere 100 I.U.”
Dr. Holick and other vitamin D advocates recommend that you obtain far more than the paltry US RDA of 200 I.U. per day. Dr. Holick suggests getting 25 to 50 percent of 1 MED over 25 to 50 percent of the skin, two to three times per week. I personally take more because I also love the peripheral feel-good benefits of spending time in the sun. There is zero risk of overdosing on solar vitamin D; your melanin/tanning mechanisms ensure that any potential excess vitamin D is destroyed on the surface of your skin before it enters the bloodstream. Historically, the only real risk of vitamin D toxicity has come from ingesting dangerously high levels of overfortified and mislabeled processed foods.
If you have even a slight suspicion that your lifestyle circumstances put you at risk of vitamin D deficiency, it will be valuable to take a clinical approach to the issue. If you have an office job or commute that prevents you from receiving midday sun, live at a latitude in discord from your ancestors, are obese, a growing youth, or pregnant or lactating, or follow a grain-based diet (which can hinder calcium absorption and thus increase vitamin D requirements), this means you!
First, I highly recommend getting your blood levels tested. Make sure to request the most relevant and accurate test, which is for the circulating form of vitamin D known as 25-hydroxyvitamin D. The test may be called “25-vitamin D” or “serum 25(OH)D.” The best time to get this test is early fall, when your vitamin D levels should be at their highest after a summer of adequate sun exposure. You can order a simple, painless home test from ZRT Laboratory for $75 (ZRTlab.com). Your vitamin D levels are represented in nanograms per milliliter (ng/ml). Dr. Holick categorizes values as follows: Under 20 ng/ml is considered deficient. Under 30 ng/ml is insufficient. The ideal range is 40–60 ng/ml, with anything under 100 ng/ml being acceptable. A level over 150 ng/ ml is considered toxic, and virtually impossible to get through sun exposure and sensible eating, as mentioned previously. Second, spend some time calculating your vitamin D manufacturing particulars at this web site:
http://nadir.nilu.no/~olaeng/fastrt/VitD-ez_quartMED.html.
This handy tool allows you to input your variables to calculate a reliable estimate of your vitamin D potential for your particular skin pigment, latitude, time of year, and time of day.
When getting regular and adequate amounts of UV 3 intensity rays over large areas of your skin proves to be a difficult task, diet and supplementation comes into play. You may have heard certain foods touted as vitamin D powerhouses: wild salmon, mackerel, herring, catfish, cod liver oil, eggs. These all provide good nutrition, but they only deliver somewhere between 200 to 1,000 I.U. on a typical serving—not nearly enough to make a dent in the bigger picture of overall vitamin D requirements. Conventional wisdom has long touted a good old glass of milk for a vitamin D boost, yet it delivers a mere 100 I.U. By contrast, when I play one of my summertime, two-hour Ultimate Frisbee matches (playing for the “skins” team, naturally!) at 34 degrees latitude in Los Angeles, with my Scandinavian skin pigment, my body manufactures about 15,000 I.U. of solar vitamin D. Got Milk? No, but thanks anyway!
