Most people know that not getting enough sleep can pack a punch on physical and mental wellbeing. This is true not only in the day or days following a night of acute sleep deprivation, but it’s especially true over the long term. Chronic, low-grade lack of sleep can take a serious toll on our health. More and more research has come in to suggest that sleep is not at all a passive act — it’s an active act, so to speak, and the brain is carrying out extraordinarily important processes during sleep.

Chronic, low-grade lack of sleep can take a serious toll on our health.

Many neurons (brain cells) continue to fire during sleep, hammering down the new information we’ve learned during the day, consolidating memories, and regulating body functions. In fact, lack of sleep has been shown to increase our risk for heart attack and stroke, and it can significantly suppress immune function and resistance.

The latest research is showing that sleep plays even bigger roles in weight and metabolism, brain function, and even sexual function than was previously thought. And, perhaps not surprisingly, it’s just as important in kids and babies as it is in adults. This article will outline some the latest sleep research, which is uncovering some exciting connections. We’ll also offer some tips on how to catch some more zzz’s if you’re not getting enough — and most people aren’t.

Lack of Sleep Might Mess up Your Metabolism

There’s been a lot of research to suggest that weight and sleep are intimately linked. Lack of sleep can be detrimental to the waistline for obvious reasons: you’re up at night and head to the kitchen for a night snack, and the next day, fatigued from lack of sleep, you look to a sugary treat to boost your energy level. Earlier studies have shown that after just a couple of nights of sleep deprivation, people report being hungrier and eat the equivalent of an entire meal more than well-rested peers. These earlier works have also linked variations in the hunger hormones, ghrelin and leptin, to sleep quality.

Men who were deprived of sleep had slower metabolisms: that is, their bodies burned fewer calories while at rest (up to 20% in some cases) than well-rested peers.

Now, a new study shows that loss of sleep actually slows down your metabolism, which can lead to weight gain. College men got either a full night’s sleep or were deprived of sleep for a 24-hour period. Their hormone levels, energy expenditure, and eating habits were all measured the next day. Men who were deprived of sleep had slower metabolisms: that is, their bodies burned fewer calories while at rest (up to 20% in some cases) than well-rested peers. The levels of hunger hormones, stress hormones, and blood sugar levels were all higher in the sleep-deprived men. The authors conclude that these changes in metabolism may be the missing link between sleep deprivation and obesity that prior studies have found.

Blood Glucose Can Suffer from Sleep Loss
Building on the sleep-hormone connection, another study has found that lack of sleep may worsen blood glucose control in diabetics. However, it does not seem to affect glucose levels in healthy people. Diabetics who lost sleep had higher blood sugar and insulin levels, and significantly more insulin resistance than well-rested diabetics. The authors of the study say that it’s possible that since diabetics already have compromised glucose and insulin control mechanisms, the effect of sleep deprivation on their body chemistry is more obvious. An earlier study had found that even in healthy subjects, insulin sensitivity was severely compromised when the participants were sleep deprived.

While researchers are hashing out all the links between sleep, metabolism, hormone levels, and weight, it’s a good idea to watch your calorie intake when you are sleep-deprived — getting enough sleep in the first place goes without saying.
Sleep Deprivation Affects How the Brain Functions and Ages

Given that sleep is a product of major changes in the brain’s activity patterns, it’s not surprising that lack of sleep affects our cognition, learning, and attention. One recent study found that lack of sleep in rats was linked to groups of brain cells taking random "catnaps" throughout the day, even when the animal was awake. This neural napping was itself linked to errors in judgment when the rats tried to perform simple acts like reaching for pellets of rat chow. Do the findings apply to humans, too? Absolutely. The author of the study says that these "tired neurons in an awake brain may be responsible for the attention lapses, poor judgment, mistake-proneness and irritability that we experience when we haven't had enough sleep, yet don’t feel particularly sleepy."

Researchers calculated that the loss in brain function linked to too much or too little sleep was the equivalent of being 4-7 years older than a well-rested brain.

Other studies have found that loss of sleep affects our ability to make quick, gut-level decisions that involve the rapid processing of outside information. The effect is pronounced enough, say the authors, that lack of sleep could affect the outcome of split-second life-or-death decisions in people like firefighters or policemen.

Getting too little – or too much – sleep has also been linked to worse performance on cognitive tests measuring verbal and reasoning abilities. A study followed middle-aged people for five years, tracking their sleep habits and cognitive prowess. Sleeping for less than six or more than eight hours was linked to deficits in cognition. Specifically, people whose average amount of sleep changed over time (becoming either longer or shorter than it had been) had more problems with cognition. The effects were so strong that the researchers calculated that the loss in brain function linked to too much or too little sleep was the equivalent of being 4-7 years older than a well-rested brain.

Sleep deprivation may also lead one to make poor economic decisions. In one study, people who were sleep-deprived made riskier financial choices in a decision-making task than well-rested participants. Even more, the parts of their brains associated with positive outcomes were more active, and those associated with negative outcomes were less active, implying that people are slightly more deluded about their decisions when they are sleep-deprived.

Since the many mechanisms involved in sleep and cognition are still somewhat unclear, researchers will continue to study the relationship. But when you have a big event coming up – perhaps one in which important decisions will be made – it’s crucial to get enough sleep the night before.

Sleep Deprivation Linked to Sexual Function

Sleep disorders like obstructive sleep apnea (OSA) affect the sleep of millions of Americans. And OSA may have a connection to a disorder that you would never think of: erectile dysfunction (ED) in men. In one new study, men who had ED suffered from OSA twice as much as those without. And the more severe the ED, the more likely the men were to have OSA. This study did not show a cause-and-effect relationship, however, so the exact nature of the nature of the relationship is still unclear. But earlier studies have arrived at similar findings: one large review found that sleep disorders like sleep apnea and insomnia were linked to ED, and that ED might actually be helped by treating the person’s sleep disorder.

Men who had ED suffered from OSA (obstructive sleep apnea) twice as much as those without. And the more severe the ED, the more likely the men were to have OSA.

Even studies in mice have found that after being subjected to oxygen deprivation during sleep (which is similar to what happens in OSA), mice experienced declines in erections and were less interested in sex than other male mice. The researchers in this study also discovered that a reduction in blood vessel function may be behind the connection (since erections rely on increased blood flow). But again, the relationship between sleep and sexual function (in men) is still somewhat foggy and more research is being done to understand it.

Sleep is Critical for Kids, Too

Though they may not always believe it, children and babies need their sleep, too. One reason, according to a new study, is that sleep is linked to growth spurts in infants. Bursts of increased sleep, where infants slept much more than usual for a couple of days (up to several hours, both from increased nap and night sleep) were linked to growth spurts, periods of concentrated growth. The sleep bursts often preceded the growth spurts by about 48 hours, serving almost as a signal that an increased period of growth was about to occur. The connection may exist because growth hormone is secreted during sleep, but the exact mechanism is still unclear.

Each additional hour of sleep was also linked to a whopping 61% reduction in the odds of being overweight/obese by the time the kids were 7 years old.

Just as sleep is linked to metabolism and weight issues in adults, it plays a similar role in children. Researchers measured kids’ body mass index (BMI), activity levels, and the amount of fat and non-fat mass (i.e., muscle and bone) the kids carried around with them. They also tracked the kids’ sleep habits, and other lifestyle factors, from the time kids were 3 until they were 7 years old. They found that for every additional hour of sleep the kids got per night, their BMI was almost half a point lower than kids who slept less.

Each additional hour of sleep was also linked to a whopping 61% reduction in the odds of being overweight/obese by the time the kids were 7 years old. After the researchers teased apart the data, they learned that the changes in weight were indeed due to fat mass, rather than non-fat mass. They suggest that the effects observed here may be due to a couple of different factors. One is behavioral: if kids are awake more, they simply have more time to snack, even if they’re not hungry; additionally, fatigue during the day can make kids less likely to be active and burn off calories. The other mechanism is biological: changes in hormone levels brought on by lack of sleep may also cause kids to feel hungrier, suggest the researchers, just as with adults.

Tips for a Good Nights’ Sleep

The NIH estimates that upwards of 60 million Americans experience sleep problems, either chronically or occasionally. How well you sleep during just one night can make or break your day, and as we’ve seen, chronic sleep problems have important long-term health implications for body and mind. The National Sleep Foundation offers some tips on optimizing your sleep so you’ll function your best.

  • Keep a schedule: set up a sleep schedule and stick to it, both on weekdays and weekends.
  • Get into a relaxing routine. Take a hot bath or read a book — but don’t pay bills or play video games, as these can be too rousing.
  • Make your room sleep-conducive. Dark, quiet, cool, and soothing should do the trick.
  • Sleep on a comfy bed and pillows. Check that your mattress is still in good shape, and your pillows offer good support.
  • Only use your bedroom for sleep and sex. No TV, video games, or other stimulating activities should be done in this room.
  • Don’t eat within 2-3 hours of going to bed, since doing so can make you feel uncomfortable and less likely to sleep well.
  • Exercise regularly, as this can boost sleep (but don’t exercise close to bedtime, since it can be too energizing close to bedtime).
  • Avoid caffeine (even in teas and chocolate) 6-8 hours before bed.
  • Don’t smoke before bed (or ever!), since nicotine is a stimulant.
  • Alcohol causes people to wake up more at night, so avoiding it before bed is wise.