By Dr. Mercola
About 1 in 3 Americans gets less than seven hours of sleep a night and more than 83 million adults in the U.S. are sleep-deprived.1,2 If you work long hours, have a sleep disorder or spend a lot of time in front of electronic screens, you may be sleeping five or fewer hours per night. Such little sleep can trigger a wide range of health issues, such as chronic disease, increased risk of accidents, reduced sex drive and weight gain.
You may not realize sleep also plays an important role in memory formation, and chronic sleep dysfunctions such as sleep apnea have been shown to accelerate memory loss. Earlier in life I disregarded the importance of sleep, at times getting no more than five or six hours a night. Now, because I value sleep as a significant factor with respect to my health and longevity, I get the recommended eight hours most nights.
I have said it many times before, and I hope you are taking this advice to heart: Most adults need about eight hours of sleep per night to function well. Children and teenagers, because they are still growing and developing, require nine or more hours of rest. As you likely have observed, it is also common for them to sleep even longer on weekends.
Sleep Deprivation: A Serious Threat to Society
Matthew Walker, Ph.D., professor of neuroscience and psychology, and founder and director of the Center for Human Sleep Science at the University of California, Berkeley, defines sleep deprivation as sleeping less than seven hours a night.
"No aspect of our biology is left unscathed by sleep deprivation," says Walker. "It sinks down into every possible nook and cranny.”3 Sleep deprivation, he notes, is associated with a number of serious diseases, including Alzheimer's disease, cancer, diabetes, heart disease, mental illness, obesity and stroke.
In an interview with The Guardian,4 Walker points out how easy it is to observe sleep problems: “I get on a flight at 10 a.m. when people should be at peak alert, and half of the [passengers on the] plane [have] immediately fallen asleep.” According to a Gallup Poll,5 Americans slept an average of 7.9 hours a night in 1942, but only 6.8 hours in 2013. Walker pins the blame for our consistently declining slumber patterns on the following “enemies of sleep:”
- Alcohol and caffeine: These and other substances, such as sleeping pills, interfere with sleep quality and sleep time
- Artificial lighting: We have effectively electrified the night, and light at night damages your health by degrading your sleep
- Loneliness, anxiety and depression: The longing for connection and the effects of mental illness can often interfere with or cause people to forego sleep
- Long work hours: The international business environment, increased global competition and longer commuter times are just a few of the factors contributing to the increase in work hours and stress-related burnout
- Overcommitment: Schedules are filled from morning to night, and many people are unwilling to trade entertainment or socializing with family and friends for sleep
Interesting Facts About Our Global Sleep Problem
Below are some intriguing facts about our global sleep problem that may surprise you:6
Two-thirds of adults in developed nations fail to receive the World Health Organization’s recommended eight hours of sleep per night
A 2013 study7 reported men who slept too little had sperm counts 29 percent lower than those who regularly got a full night’s sleep
You are 4.3 times more likely to be involved in a crash than a well-rested driver when you drive on less than five hours of sleep; on just four hours of sleep, your risk of crashing is 11.5 times higher
A hot bath before bed readies you for sleep because it causes your dilated blood vessels to radiate inner heat, lowering your core body temperature, which is an essential activity to initiate sleep
More than 100 diagnosed sleep disorders exist, the most common of which is insomnia
The global population comprises 40 percent morning types, those who prefer to awaken at or around dawn; 30 percent evening types, those who go to bed late and wake up late; and 30 percent who are classified as somewhere in between
Why Is Lack of Sleep a Badge of Honor While Healthy Sleep Is Vilified?
According to Walker, for whatever reason, lack of sleep in modern times has become a sort of “badge of honor.” You may feel compelled to talk about how busy you are or how much you are accomplishing, even if pushing yourself to do increasingly more is causing you to damage your health by foregoing sleep.
On the other hand, good sleep can sometimes be characterized as a sign of sloth. “We have stigmatized sleep with the label of laziness,” says Walker. “We want to seem busy, and one way we express that is by proclaiming how little sleep we’re getting.”
Walker asserts no one would look at an infant and suggest he or she was a lazy baby. That’s the case because “we know sleeping is nonnegotiable for a baby.” Unfortunately, the notion that sleep is vital to our well-being is quickly dispensed with as we age. “Humans are the only species that deliberately deprive themselves of sleep for no apparent reason,” suggests Walker.
Based on years of studying sleep, he is certain there is not a single person on the planet who can make it on five hours or less of sleep without suffering some level of short-term impairment or long-term illness. When asked if he takes his own advice about sleep, Walker replied:
“I give myself a nonnegotiable eight-hour sleep opportunity every night, and I keep very regular hours. If there is one thing I tell people, it’s to go to bed and to wake up at the same time every day, no matter what. I take my sleep incredibly seriously because I have seen the evidence.
Once you know that after just one night of only four or five hours of sleep, your natural killer cells — the ones that attack the cancer cells that appear in your body every day — drop by 70 percent, or that a lack of sleep is linked to cancer of the bowel, prostate and breast … how could you do anything else?”
Sleep Affects Your Body’s Hunger-Regulating Hormones
You may not realize a lack of consistent, high-quality sleep wreaks havoc on two of your body’s hunger-regulating hormones. Chronic lack of sleep can cause ghrelin — also known as your “hunger hormone” — to skyrocket, which has the effect of making you feel hungry when you really don't need to eat. Ghrelin appears to act on your brain’s pleasure centers. This explains why you may be inclined to reach for a second brownie based on remembering how good the first one tasted and made you feel while you were eating it.
Leptin, also referred to as the "obesity hormone," helps regulate your appetite, metabolism and feelings of satiety. Leptin tells your brain when you’re full and when it should start burning calories. When you are sleeping, your leptin levels increase, signaling your brain you have sufficient energy and letting it know to curtail any calorie burning or signals for hunger.
The decrease in leptin brought on by sleep deprivation often results in your metabolism slowing down and your body signaling a constant feeling of hunger even though you do not need to eat. Because leptin is secreted by fat tissue, if you are overweight, you likely have higher than normal levels of leptin, which may lead to leptin resistance.
Overly high levels of leptin have been tied to heart disease, high blood pressure, obesity and stroke, as well as blood sugar problems.8 If you are leptin resistant, your body will receive signals that may lead you to continue to eat even when you’ve actually had enough. While chronic sleep deprivation cannot shoulder total responsibility for the continuing surge in global obesity rates, Walker believes it certainly plays a significant role. He states:9
“I’m not going to say the obesity crisis is caused by the sleep-loss epidemic alone. It’s not. However, processed food and sedentary lifestyles do not adequately explain its rise. Something is missing. It’s now clear sleep is that third ingredient.”
The researchers stated, “These differences in leptin and ghrelin are likely to increase appetite, possibly explaining the increased BMI observed with short sleep duration.” 11 A sleep disorders study involving more than 1,000 participants, which was designed to uncover a link between sleep problems and metabolic hormones, concluded:10
- Those who slept for five hours had 14.9 percent higher ghrelin levels and 15.5 percent lower leptin levels than those who achieved eight hours of sleep
- The short sleepers had higher body mass indexes (BMIs)
Running Low on ZZZs May Put You at Risk for Alzheimer’s Disease
While working on his Ph.D. in neurophysiology, Walker stumbled into the realm of sleep. After failing to successfully identify brainwave patterns in people with different forms of dementia while testing them during daytime hours, Walker stumbled across a scientific paper revealing a probable link between sleep and dementia. In the ensuing six months, Walker set up a sleep laboratory and began to study his patients’ brainwave patterns at night. In doing so, he found that sleep quality, it seemed, could be an early diagnostic for dementia.
Now, Walker is convinced too little sleep during your adult life span significantly raises your risk of developing Alzheimer’s disease. This is the case because amyloid-beta deposits that would normally be cleaned out of your brain nightly during deep sleep accumulate as plaques and kill off surrounding cells.12 This waste removal system has been dubbed the glymphatic system, and operates similarly to your body's lymphatic system, which is responsible for eliminating cellular waste products.
Because your brain is a closed system, protected by the blood-brain barrier, it needs its own system for waste elimination. Your glymphatic system gets into your brain by piggybacking on blood vessels in your brain. By pumping cerebral spinal fluid through your brain's tissues, your glymphatic system flushes waste from your brain back into your circulatory system for elimination by your liver.
Because your glymphatic system ramps up its activity during sleep, when you don’t get enough sleep, the damaging plaques build up, attack and degrade particular regions of your brain.
Walker notes a brain affected by Alzheimer’s has lost most of its ability to remove the amyloid-beta waste products, mainly because it is caught in a vicious cycle: more amyloid, less deep sleep; less deep sleep, more amyloid. If you are not sure of the steps you can take to help prevent Alzheimer’s disease, please review my previous article “Alzheimer’s Disease — Yes, It’s Preventable!”
Lack of Quality Sleep Contributes to Chronic Pain
A U.K. study13 published in Sleep Medicine Reviews suggests poor sleep makes you two to three times more likely to develop a chronic pain condition, while also putting you at risk for other health problems. “Sleep and pain problems are two of the biggest health problems in today’s society,” said lead author Esther Afolalu, a Ph.D. student in the department of psychology at the University of Warwick in Coventry. Afolalu and her colleagues reviewed 16 prior sleep studies involving more than 60,000 adults from 10 countries.
The studies looked at how well people were sleeping at the onset of the research as well as the effects of longer-term sleep changes on participants’ immune function, pain and physical health. Half the participants were tracked upward of four years.
Afolalu and her team wrote: “A decline in sleep quality and sleep quantity was associated with a two-to-three-fold increase in the risk of developing a pain condition, small elevations in levels of inflammatory markers and a decline in self-reported physical health status.” Based on the research, if you do not get adequate sleep, you may be at risk for:
- Reduced ability of your immune system to fight off bacteria, viruses and other foreign substances
- Increased levels of inflammation
- Higher levels of the stress hormone cortisol
- Increased levels of other biomarkers related to fatigue, pain and poor health
- Deficits in physical functioning
Notably, Afolalu and her team discovered recently developed insomnia doubles your risk of a chronic pain disorder and hip fracture problems. While increases in sleep did not appear to directly diminish pain or arthritis, improved sleep did help participants function better physically. Keep in mind Afolalu’s research has two notable limitations: reliance on individuals to self-report their sleep patterns and a lack of consistent tools for measuring sleep quality and quantity.
Poor Sleep, Depression and Your Brain’s Reward Center
While the precise causes of depression are not always evident, certain factors such as poor sleep have been shown to contribute to it.14 Insomnia, for example, has been shown to influence the onset, severity and recurrence of depressive episodes. If you routinely suffer from insomnia, you are at twice the risk of developing depression as compared to individuals who sleep well.
A study published in the Journal of Neuroscience15,16 suggests your brain’s reward center may help protect you from the depressive symptoms traditionally associated with poor sleep. Researchers at Duke University have taken a closer look at the involvement of your ventral striatum (VS) — an area of your brain responsible for reward processing and motivation. Their objective is to better understand the role your VS may play with respect to depression and poor sleep.
Dysfunction in your VS is thought to be associated not only with depression, but also with addiction, bipolar disorder, obsessive-compulsive disorder and Parkinson’s disease. Because poor sleep is not necessarily associated with depression in every individual, researchers have found that stimulating the VS region of the brain has a therapeutic effect on some depressed patients.
Reut Avinun, Ph.D., department of psychology and neuroscience, Duke University, and her colleagues engaged more than 1,000 university students to explore the relationship among depression, self-reported sleep patterns and VS activity.
Functional magnetic resonance imaging data collected while study participants played a card-guessing game designed to engage the VS indicated students with higher reward-related VS activity were less likely to report symptoms of depression even when their sleep quality was poor. Avinun said:17
"In our study, we showed how the negative effects of poor sleep can also be modulated by [the ventral striatum], so high reward-related activation can buffer the effect of poor sleep on depressive symptoms. This same region has been associated with optimism, so it's possible individuals with this high reward responsiveness can cope with stressful and negative experiences better by having a more positive outlook."
Further research in this area may help scientists gain further insight into how depression works, as well as assist them in identifying biomarkers for depression risk. Says Avinun: "In the future, I plan to work on gaining a better understanding of depression susceptibility, and help to identify the individuals who are more at risk of developing depression by looking at their brain and DNA."
Is Your Chronic Sleep Problem Caused by Sleep Apnea?
Some 30 million adult Americans suffer from undiagnosed sleep apnea,18 a serious health condition which causes you to stop breathing while you are sleeping. Depending on the severity of your condition, these breath interruptions may occur just a few times — or hundreds of times — an hour. During these moments without breath, your brain and the rest of your body is literally being starved of oxygen.
If you have undiagnosed sleep apnea, you may be unknowingly putting yourself at risk for diseases such as diabetes, heart disease and stroke. In addition, sleep apnea can contribute to depression, insomnia, impotence, pregnancy complications and weight gain. Clearly sleep apnea is not something to be taken lightly.
Sleep apnea can often go unnoticed because doctors don’t routinely screen for it and you may be inclined to dismiss daytime sleepiness as “a bad night’s sleep” or stress. If you suspect you may be suffering from sleep apnea, you’ll want to seek the help of a qualified sleep specialist. Ask your general practitioner for a recommendation, and also do your own research. Some sleep doctors offer solutions focused on addressing only secondary problems, while you will want to uncover and treat the root issue(s).
Treatment Options for Sleep Apnea
Potential treatment options for addressing sleep apnea are as follows:
- Buteyko Breathing Method: The Buteyko technique, which is named after the Russian doctor who developed it, is useful to reverse health problems caused by improper breathing, including sleep apnea
- Continuous Positive Airway Pressure (CPAP): CPAP is a special type of sleeping mask prescribed for severe sleep apnea, which is designed to mechanically restore your breathing by applying air pressure to open your airway
- Orofacial Myofunctional Therapy: Myofunctional therapy involves the neuromuscular reeducation or repatterning of your oral and facial muscles, including facial and tongue exercises and behavior modification techniques to promote proper tongue position, improved breathing, chewing and swallowing
- Oral appliance: If you have mild to moderate sleep apnea related to jaw or tongue issues, dentists specializing in sleep apnea can design a custom “mouth guard” you can wear while sleeping to facilitate proper breathing
- Weight loss: Because obesity and sleep apnea often go hand in hand, you may be able to dramatically relieve the effects of sleep apnea simply by losing weight; weight loss will reduce pressure on your abdomen and chest, thereby allowing your breathing muscles to function more effectively when you sleep
When it comes to how you breathe, your diet may play a bigger role than might imagine. Processed foods, which tend to acidify your blood in an attempt to maintain normal pH, cause you to breathe more heavily and can lead to chronic overbreathing. As such, processed, high-protein and high-grain meals have been shown to have negative effects on the way you breathe. Give your body a break by consuming more water, fruits and vegetables, which have lesser impact on your breathing.
Sleeplessness Is Having a Catastrophic Effect on Health and Well-Being
In the video above, Walker asserts his belief that getting sufficient quality sleep is the single most effective thing you can do to reset your brain and body and invigorate your health on a daily basis. I agree wholeheartedly. You may be surprised to know the World Health Organization, since 2007, has tagged shift work as a “probable human carcinogen” because it causes circadian disruption.19
While this news may surprise you, the truth is if you work erratic hours, particularly the night shift, you most assuredly are putting yourself at greater risk for diseases such as cancer, diabetes and obesity. While you may not be a shift worker, you very likely are wrestling with one or more issues that are causing you to sleep poorly.
No matter the root issue(s) you face, research linking chronic poor sleep and lack of sleep to disease and illness cannot be ignored. The scientific facts underscore my belief that there is no substitute for, nor any excuse for not getting, a full night’s rest. Says Walker:20
“The decimation of sleep throughout industrialized nations is having a catastrophic impact on our health and wellness. It is a silent sleep-loss epidemic. It’s time for us to reclaim our right to a full night of sleep, without embarrassment or the stigma of laziness. In doing so, we may remember what it feels like to truly be awake during the day.”
Given its importance, I encourage you to take a few moments today to evaluate your sleep habits. Are you getting enough sleep? If not, what’s one change you can make to improve the length and/or quality of your sleep? If you need help getting started, check out my 16 Chronological Tips to Improve Your Sleep.