I used to think sleeping was meant just to recharge your batteries after a long day. I often thought it was a waste of time. After all, if you sleep away part of the day, there’s not enough time left to get everything done. As a society we associate sleeping late with laziness and a poor worth ethic, whereas waking early is equated with success and worth.
However, a poor night’s sleep not only makes you feel tired and fatigued; it also increases your risk for developing disease. When you are rebuilding from a chronic health issue, a loss of sleep will hinder your ability to do so, and it may increase your chances of recurrence or an exacerbation of that condition. New research is uncovering the link between sleep deprivation and heart disease, cancer, diabetes, immune dysfunction, obesity, and increased mortality. Sleep is anything but a waste of time.
Sleep Loss and Disease
How much sleep is the right amount? Seven to eight hours per night. Anything less is generally considered to be sleep loss. Too much sleep, or not enough, may be an indication of a more serious health issue. The main symptoms of sleep loss are excessive sleepiness during the day, fatigue, poor memory and concentration, irritability, and often a depressed mood. Not enough sleep can also delay reaction time, and make you distracted, causing mistakes (like spilling scalding coffee on your foot!).
There are many causes of sleep loss; some are self-inflicted, while others have an organic or physical reason.
Basically, sleep is a reversible period of physical and mental inactivity, whereby we are less responsive to external stimuli. When your mind and body are “offline” during sleep, the body goes through physical changes, including reduction in blood pressure, body temperature, respiration, and heart rate. However, while certain functions of the body slow down during slumber, other activities increase. For example, as soon as you fall asleep, your brain releases growth hormone (GH), which stimulates cell growth and activates cellular regeneration. GH helps regulate metabolism, deflates fat cells, helps regulate blood sugar, and promotes protein synthesis in cells.
Your body has its own internal clock to control its natural sleep-and-wake pattern. This clock also controls how much of the sleep hormone melatonin is produced. Melatonin is secreted into the blood in a rhythmic manner, peaking in the dark hours of the night and dropping during the day. Exposure to light abruptly suppresses the release of melatonin in the body.
During sleep and the release of growth hormone and melatonin, cells are busy repairing themselves, wounds are healing, and the brain is trucking out metabolic waste products at a rapid pace. Unfortunately, because of our fast-paced world, sleep loss has increased in recent years, causing numerous behavioral and physiological changes. Recent studies have reported associations between sleep loss and inflammatory responses as well as the progression of heart disease, cancer, diabetes, obesity, and other chronic health crises.
SLEEP DEPRIVATION AND INFLAMMATION
Inflammation is the key physiological catalyst in all chronic diseases. A high-calorie, nutrient-deficient diet, too much body fat, stress, and a toxic environment all increase levels of inflammation. Research is revealing that partial or total sleep loss increases the inflammatory agents IL-1, IL-6, TNF, and CRP.
Studies in Brain, Behavior, and Immunity and the Archives of Internal Medicine state that sleep disturbance turns on genes that cause inflammation. During the inflammatory response, white blood cells produce inflammatory messengers called cytokines. Some cytokines communicate with other white blood cells to join in the inflammation; others, including IL-6, TNF, and CRP, are associated with a greater risk of developing heart disease, diabetes, certain cancers, obesity, and other inflammatory diseases, such as rheumatoid arthritis and Crohn’s disease. In the journal Practice & Research Clinical Endocrinology, researchers showed a reduction of sleep by just two to four hours a night increased levels of IL-6, TNF, and CRP.
According to a study in the Journal of Allergy and Clinical Immunology, sleep loss produced significant increases in blood levels of TNF-alpha and IL-6—messengers that affect the nervous, hormonal, and immune systems. In a study found in Best Practice & Research Clinical Endocrinology, investigators also found each hour of reduced sleep (which is not much) increased circulating levels of disease-promoting cytokines. Last, a study in Biological Psychiatry showed that a single night of sleep reduced by 50 percent resulted in the activation of NF-kB, the orchestrator of inflammation. When turned on, NF-kB causes the increase of pro-inflammatory agents, thus setting the stage for disease.
SLEEP DEPRIVATION AND HEART DISEASE
Coronary artery disease is an inflammatory condition involving an interaction between free radicals and the immune system in the walls of the arteries that supply blood to the heart. Data from the Journal of Pineal Research showed melatonin to be cardio-protective by reducing cellular damage and preventing oxidation of LDL. Several studies, including a study out of the Lancet, also showed that people with coronary artery disease and hypertension have significantly lower melatonin levels. In fact, they found that the lowest levels of melatonin correlated with increased severity of disease.
Another study in Best Practice & Research Clinical Endocrinology found sleep deprivation to increase blood pressure and cause alteration in the endothelium. Since the endothelium is the barrier between the circulating blood and the artery itself, dysfunction of the endothelium allows white blood cells and unwanted material to pass into the wall of the artery. In addition, endothelial dysfunction will cause unwanted platelets to stick to the wall of the artery and cause constriction, leading to high blood pressure.
Last, research published in the European Heart Journal found that short and long durations of sleep are predictors of cardiovascular outcomes. The data the authors gathered showed that short sleepers (fewer than seven to eight hours per night) have a greater risk of developing coronary artery disease and stroke, whereas those sleeping five hours or fewer should be considered at high risk for cardiovascular disease and mortality.
SLEEP DEPRIVATION AND CANCER
Researchers continue to study the biological effects of sleep deprivation on diseases like cancer. Sleep loss has been shown to disrupt immune function and increase inflammation, both of which promote the development of cancer. Melatonin secretion, which is stimulated by darkness and decreased by light, has multiple effects on the cancer microenvironment. Studies discussed in the Journal of Medicine and Life showed that melatonin had profound effects on tumor biology. It was found to reduce cell proliferation and tumor growth, and to inhibit blood vessel development to tumors. Melatonin also participates in activating the immune system needed to prevent tumor development. Fascinating evidence reveals this powerful sleep hormone prevents cancer cell metastasis and invasion into other tissues.
Melatonin was also found to protect against estrogen-driven breast cancer. Estrogen is involved in many aspects of the malignant process, including cellular proliferation, angiogenesis (blood vessel development), and metastasis. A study in the Journal of Biological Chemistry showed that melatonin blocked the stimulating effects of estrogen on breast cancer cells. Additional studies demonstrate that melatonin levels are diminished in breast cancer, and peak nighttime blood concentrations of melatonin are dramatically lower in breast cancer patients.
Quality sleep is important to healing and proper immune function, making it essential to get no less than seven to eight hours of sleep. For those dealing with cancer, sleep loss is a serious hazard. Studies in recent years have shown the link between sleep loss and the top forms of cancer. Research from Cancer Epidemiology, Biomarkers and Prevention, Cancer, and Breast Cancer Research and Treatment all found that those who experienced loss of sleep were more likely to develop colorectal, prostate, and breast cancers. The studies also showed that women who chronically lost sleep not only were at a greater risk for developing breast cancer, but developed a more aggressive type of breast cancer.
Many types of cancer are created by DNA damage from ionizing radiation, toxins, or a lack of nutrients. When DNA is damaged, specific tumor-suppressor and DNA-repair genes become active, producing protein to repair the broken DNA material. For a multitude of reasons, these repair mechanisms fail to do their jobs, and cancer develops. Sleep and the circadian rhythm are another backup system that helps in the repair. The circadian rhythm gene NPAS2 has been shown to help in DNA repair, and it acts as a tumor suppressor.
Emerging evidence suggests that disruption in sleeping and the circadian rhythm increases the risk of developing cancer. The hormone melatonin appears to be a key factor in preventing carcinogenesis and all stages of cancer progression. Sleep loss disrupts the circadian rhythm and the release of melatonin, setting us up for the development and progression of cancer.
SLEEP DEPRIVATION, DIABETES, AND OBESITY
Sleep loss is linked clearly to the development and progression of both heart disease and cancer. It can also lead to impaired glucose tolerance and diabetes. While you sleep, your body must maintain normal circulating blood sugar levels so your brain can continue to function in the absence of food. When you sleep less than seven to eight hours, you increase your chances of developing diabetes. A study in the Archives of Internal Medicine found that those who did not get a full seven to eight hours of sleep, as well as those with interrupted sleep, developed impaired glucose tolerance and an increased incidence of diabetes. It has been proposed that a lack of sleep acts as a stressor, causing the release of the stress hormone norepinephrine. Norepinephrine causes the release of fatty acids from fat cells, which can lead to insulin resistance and unmanaged blood sugar. Sleep deprivation was also found to alter growth hormone and cortisol secretion, both of which interrupt normal blood sugar levels.
When you fall asleep (assuming you haven’t just eaten a big load of carbs), there is less circulating insulin and less sensitivity to insulin, making cells less tolerant to glucose. As the night progresses, glucose tolerance begins to improve, and blood sugar levels begin to decrease before waking. Sleep loss and interrupted sleep both disrupt insulin function and blood sugar regulation. Another association between blood sugar issues and sleep loss is inflammation. Sleep loss increases the inflammatory cytokine IL-6, which has been shown to contribute also to insulin resistance and abnormal blood sugar.
Sleep deprivation can contribute directly to the development of insulin resistance and diabetes by causing problems of glucose regulation, and indirectly through changes in appetite that can lead to being overfat or obese. Obesity is a major risk factor for insulin resistance and diabetes. There are two major hormones that regulate appetite: ghrelin and leptin. Ghrelin, from the stomach, will make you feel hungry, while leptin from your fat cells makes you feel full. When you don’t get enough sleep, your level of ghrelin goes up, and your level of leptin goes down. This can lead to changes in your appetite where you feel hungrier when sleep-deprived than you do when well-rested, causing you to overeat and increasing your risk of becoming overfat or obese.
A study from the American Journal of Nutrition found sleep loss caused people to eat excessive high-energy snacks rather than meals. While higher ghrelin and lower leptin levels were found, those who did not get enough sleep were also physically less active. Both increased appetite and lack of physical activity also play a major role in the development of an unhealthy body composition. Basically, not enough sleep increases your appetite, thus causing you to overeat high-calorie foods with higher carbohydrate content. Consequently, you become physically less active, which ultimately throws off your energy balance and leads to higher body fat and obesity.
Beyond an unhealthy body composition, high body fat increases inflammatory cytokines (IL-6, TNF) that are implicated in all chronic disease. High body fat increases insulin resistance, a major contributor to the development and progression of cancer. Overeating high-calorie, high-sugar foods can also mean eating fewer nutrient-dense foods, which is proven to cause disease.
Rebuild with a Good Night’s Sleep
Getting to sleep can sometimes be a challenge. Here are some strategies to improve your quality of sleep and ensure you are getting enough sleep. To start, make sure your bedroom and your bed are comfortable, then use these tips:
Summary
A good night’s sleep is not only one of the most satisfying experiences; it is also crucial to good health. A solid seven to eight hours of uninterrupted sleep help you maintain normal mental function and energy levels, promotes rebuilding and repair of cells and tissues, improves immunity, and staves off disease.
However, less than seven to eight hours of sleep per night makes it rough to get through the day, and will cause the development and progression of the most serious diseases, including heart disease, cancer, blood sugar issues, and diabetes. Sleep loss will also increase inflammation and cause you to overeat high-calorie foods, thus contributing to being overfat and prone to disease.
Last, with our fast-paced lives and drive to get things done, on top of exposure to too much indoor and outdoor lighting, many of us suffer from low levels of melatonin. Since melatonin protects us from disease (and not producing enough can cause disease), we need to follow the strategies listed previously in order to get adequate sleep so our bodies can rebuild from disease.