Understanding the reasons we sleep has been a subject of study for years. Although scientists haven’t yet discovered all that occurs during sleep, there have been unique discoveries leading to a better understanding of cognitive1 and physical health.2,3
The Centers for Disease Control and Prevention finds 1 in 3 Americans don’t get enough sleep4 and note insufficient sleep is linked with a wide variety of health problems.5 For example, getting less than five hours of sleep each night may double your risk of heart disease or stroke.6 Researchers have also found a persistent link between sleep deprivation, weight gain7 and insulin resistance.8
Sleep deprivation also influences your mental and cognitive abilities and emotional well-being. One of the reasons sleep deprivation is so detrimental is it doesn’t impact just one aspect of your health: It impacts many.
In a recent study published in Diabetes Care,9 funded by the National Heart, Lung and Blood Institute, researchers found it isn’t just the number of hours of sleep each night, but also the regularity of your sleep that impacts on your health.
Erratic sleep pattern increases the risk of obesity and diabetes
Previous research has found detrimental health effects with sleep deprivation, but this new study discovered that when participants did not stick to a regular bedtime and wake-up schedules it put them at higher risk for obesity, high blood pressure, high blood sugar, and other metabolic disorders.
Researchers enrolled participants from the Multi-Ethnic Study of Atherosclerosis.10 They completed a seven-day actigraphy, which is a noninvasive way of monitoring rest and activity cycles. A sensor is worn for a week to measure gross motor activity. They were then followed for a median of six years.11
Metabolic abnormalities were defined using criteria developed for the National Cholesterol Education Program, and researchers used five cross-sectional analyses adjusted for socio-demographic and lifestyle factors.
They found that for every one-hour deviation of sleep duration, the participants’ risk of metabolic syndrome increased by as much as 27%; a one-hour deviation in timing (i.e., going to bed earlier or later than regular) was associated with 23% higher odds.12 Study author Tianyi Huang, an epidemiologist at Brigham and Women’s Hospital, commented:13
“Many previous studies have shown the link between insufficient sleep and higher risk of obesity, diabetes, and other metabolic disorders. But we didn’t know much about the impact of irregular sleep, high day-to-day variability in sleep duration and timing.
Our research shows that, even after considering the amount of sleep a person gets and other lifestyle factors, every one-hour night-to-night difference in the time to bed or the duration of a night’s sleep multiplies the adverse metabolic effect.”
Bedtime changes came before metabolic dysfunction
The study followed 2,003 men and women between the ages of 45 and 84. In addition to wearing sensors for seven days, the participants also filled out a sleep diary and answered standard questionnaires about their sleep habits and other lifestyle and health factors.14
The prospective results demonstrated variations in duration and bedtimes came before the development of metabolic dysfunction, providing evidence for a causal link between irregular sleep and metabolic disorders.
Researchers found the participants whose duration changed by more than one hour had a higher likelihood of being African-American, working non-day shift schedules, smoking and having shorter sleeping duration. Co-author Dr. Susan Redline with the Division of Sleep and Circadian Disorders at Brigham and Women’s Hospital said:15
“Our results suggest that maintaining a regular sleep schedule has beneficial metabolic effects. This message may enrich current prevention strategies for metabolic disease that primarily focus on promoting sufficient sleep and other healthy lifestyles.”
Metabolic syndrome leads to greater health challenges
Metabolic syndrome is characterized by a cluster of symptoms, including large waist circumference indicating high levels of visceral fat, high blood pressure, insulin resistance and/or high blood sugar, low high-density lipoprotein cholesterol and high triglycerides. The combination of three or more of these factors is evidence of metabolic dysfunction.16
These risk factors raise your risk for heart disease, diabetes, and stroke. Your risk is also raised even when you have “borderline high-risk factors.”17 Although a large waistline is a visible sign, the remainder has no visible signs or symptoms.
The incidence of the metabolic syndrome often parallels obesity and Type 2 diabetes. According to a global survey18 of 195 countries in 2015, 604 million adults and 108 million children were obese. Researchers have found the problems of obesity have doubled in 73 countries since 1980.
However, obesity is not always synonymous with metabolic syndrome, as scientists have found there are individuals who are obese with high levels of insulin sensitivity yet have no high blood pressure. The data on metabolic syndrome is difficult to ascertain, as many who have the condition do not carry the diagnosis and many of the factors have no symptoms.19
Some researchers believe the metabolic syndrome is three times more common than diabetes and estimate the global prevalence to be 25%. This global estimate is close to an estimation for the U.S. population. The CDC20 estimates 9.4% of the U.S. population has diabetes and three times this is 28.2%, slightly higher than the global estimation.
The high cost of sleep deprivation
Sleep deprivation comes at a steep cost to individuals and communities. For instance, third mate Gregory Cousins’ sleep deprivation led to one of the greatest environmental catastrophes in history when he ran the supertanker Exxon Valdez aground, causing 11 million gallons of crude oil to spill into Prince William Sound.21
The accident devastated 23 species of wildlife and nearly 1,300 miles of coastline habitat. As reported in The Balance, in just the first few days 140 bald eagles, 302 harbor seals, 2,800 sea otters, and 250,000 sea birds were killed.22
According to the American Sleep Association,23 37.9% of Americans report unintentionally falling asleep during the day at least once a month. Unfortunately, many skimp on sleep to “get things done.” However, the evidence shows when you skimp on sleep, you lose productivity.24
Sleep deprivation costs the U.S. economy $411 billion every year in accidents and lost productivity.25 Loss of sleep not only affects the quality of life but when individuals like construction workers, nurses, doctors, and pilots choose to push through sleep deprivation, it may have lethal consequences.
The CDC finds drowsy driving is a major problem in the U.S. and estimates it was responsible for 83,000 crashes, 37,000 injuries and 886 fatalities annually between 2005 and 2009.26 While falling asleep at the wheel is dangerous, being sleepy or drowsy makes you less attentive, slows your reaction time and affects your ability to make decisions behind the wheel.
The CDC finds those who do not get enough sleep, such as shift workers, those with untreated sleep disorders or those taking certain medications, are most likely to drive drowsy.27 Additionally, a loss of sleep increases your risk of cardiovascular disease,28,29 premature birth,30 lower academic performance,31 depression, anxiety,32 dementia, and Alzheimer’s disease.33
More sleep may help you reach your goal weight
In addition to lowering your risk for these conditions, improving your sleep time and quality may well help you with your weight loss efforts. U.K. researchers investigated the connection between sleep duration, diet and metabolic health in 1,692 adults.34 The researchers analyzed adiposity, metabolic markers, and food intake.
Blood pressure and waist circumference were also recorded. After results were adjusted for confounding factors such as age, gender, ethnicity, smoking, and socioeconomic status, the researchers found the number of sleep hours was negatively associated with body mass index and waist circumference. However, it was not associated with any dietary measures.
They found adults sleeping fewer hours were more likely to be obese.35 If you’re trying to lose weight, getting an adequate amount of sleep may mean the difference between success and failure.
Researchers at the University of Chicago found those who slept 8.5 hours lost 55% more body fat than those who slept 5.5 hours. According to these researchers,36 “Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss and related metabolic risk reduction.”
Light and EMF pollution reduces sleep quality
Your quality of sleep may be impacted by the number of hours you spend sleeping, an irregular sleep pattern and by light and electromagnetic pollution. If you have ever gone camping, you likely noticed a change in the quality of sleep you enjoyed. Chances are you slept deeper and awakened more rested.
Two influential factors resulting in better sleep outdoors and away from “civilization” are a drastic reduction in exposure to artificial lights and electromagnetic fields (EMF). Your circadian clock is affected by your melatonin levels, which is in turn affected by your exposure to light at night. This plays a role in how deeply you sleep and how well-rested you might feel the next day.
Even exceptionally dim light during sleep may have a detrimental effect on quality and quantity. Ideally, you’ll want to avoid having any light in your bedroom at night.
Consider using blackout blinds on your window if you have a street lamp outside your bedroom. Also, consider moving any alarm clock or other light-emitting devices outside the bedroom and/or wearing a sleep mask to reduce light exposure.
EMF may also impair your sleep quality37 and produce oxidative damage.38 Consider shutting off all electronic devices and your Wi-Fi at night to reduce your exposure and improve your sleep quality.
Strategies to improve your sleep quality
Sleep continues to be one of the mysteries of life. Although it was once thought to be little more than a waste of time, modern research has shed light on the crucial component sleep plays in a healthy lifestyle.
Unfortunately, sleep debt has a cumulative effect and a persistent lack of sleep may disrupt your health. The good news is there are many natural techniques you may use to restore sleep health, develop a regular pattern of sleep and enjoy high-quality sleep.
Whether you have difficulty in the early hours of the night falling asleep, waking up too often, difficulty falling back to sleep or don’t feel rested when you wake up in the morning, you will likely find tips in my previous article, “Top 33 tips to optimize your sleep routine,” to help adjust your pattern and improve your sleep quality.
Additionally, the article gives you the ideal amount of time you need to sleep depending on your age. As discussed, maintaining a natural rhythm of daylight and darkness is essential to quality sleep, and we share more about this in my interview with Dan Pardi in the article.