Dr. Josiane Broussard, an associate professor at Colorado State University and the head of the college’s Sleep and Metabolism Laboratory, believes the biggest public misconception about sleep is “probably that you can somehow adapt to not getting enough.”
Many people think of insufficient sleep—whether the product of insomnia, circumstance or lifestyle—as merely something unpleasant, or even salutary (as in, the mark of a strong work ethic). And yet the harm it does to our metabolism, immune system, professional performance, road and workplace safety and other parts of life is backed by science. The AMA Journal of Ethics stated in its October 2024 Sleep Stewardship issue that “insufficient or poor-quality sleep—like insufficient or poor-quality air, food or water—is associated with severe health consequences.”
In order to understand how poor sleep impacts our overall health, and what we can do about it, we must first understand why we might not sleep well.
How circadian rhythms work
Our brains and bodies naturally go through daily cycles of wakefulness, peak focus, fatigue and sleep—what is known as our circadian rhythm. This is colloquially referred to as our biological clock.
Our circadian rhythm is mediated by environmental and behavioral factors, including diet, temperature, socialization, exercise and light. Broussard says exercising late in the day or eating close to bedtime, for instance, speeds up our metabolism when it would naturally slow down, thereby setting our circadian clock back. Some factors are unavoidable, of course, like working late or waking up in the middle of the night to feed a crying baby.
Light is the strongest factor influencing our circadian clocks, says Natalie Rolle, program director for CSU’s Sleep Services and an occupational therapist who specializes in behavioral sleep treatments. At night, artificial light is known to suppress melatonin, making it hard to fall asleep. This is especially true of the short-wavelength blue light that shines from our phone screens, which is why sleep experts recommend avoiding screens for an hour or two before going to bed.
Research also shows that spending time outside in the morning is important for resetting our circadian clocks. Not only does this help ramp up our morning energy, but it sets us up for a gradual wind-down and healthy fatigue state when the time comes to get some Z’s.
Effects of sleep deprivation
A main way insufficient sleep affects our health is by interfering with our metabolism. Perhaps the best way to frame this issue is the question, “Why are potato chips so irresistible after a poor night’s sleep?”
Broussard says that’s because a lack of sleep affects our appetite by changing the levels of hormones that regulate hunger and satiety. The first is ghrelin, which stimulates hunger.
“Sleep loss actually increases that peptide and makes meals a little less fulfilling,” Broussard says. “Ghrelin is usually suppressed by a meal. When you’re sleep-restricted, it’s not suppressed as much.”
Another hormone, leptin, signals satiety to the brain.
“Sleep loss increases ghrelin and decreases leptin,” Broussard says. “It hits the gas and takes the foot off the break on hunger.”
Research has shown that we’re drawn to less healthy foods when we’re sleep deprived (such as high-carbohydrate evening snacks), which helps seal the relationship between insufficient sleep and weight gain. Knowing that our hormones are probably a little out of whack if we haven’t slept well can help us recognize and resist some of those temptations, Broussard says.
Insufficient sleep affects virtually every other aspect of health to varying degrees. Our immune system works to eliminate free radicals during deep sleep, so chronic sleep deprivation may influence cancer risk, according to the National Cancer Institute. Inadequate sleep also takes a toll on working memory, driving safety and mental health.
“It’s a terrible thing to be awake when reason sleeps,” Rolle says. She attributes this paraphrased piece of wisdom to Michael Perlis, a sleep medicine specialist at the University of Pennsylvania. “Good deep sleep is probably the best anti-anxiety [medication] that you’ll ever take,” she says.
Rationality declines sharply in the evenings, too, potentially worsening our mental state.
“The later it gets at night, the more emotional we are,” Rolle says. “We’re left with just the ancient part of our brain, which is our amygdala—our emotional center.”
The effects of late nights and irregular sleeping habits can carry over into daytime perceptions and behaviors. Insufficient sleep is correlated with depression, impulsivity, emotional dysregulation, lack of mental clarity and heightened symptoms in people with ADHD, according to articles published by the National Institutes of Health and the science journal, Nature. There’s also the effect of slower reaction time, which can pose dangers on the road or at work.
Insomnia treatment
For those who struggle with insomnia—a sleep disorder that makes it difficult to fall asleep or stay asleep—the most popular remedies boil down to good sleep hygiene, like creating a bedroom environment and routines that are conducive to sleep. Other examples include avoiding afternoon caffeine intake, investing in a comfortable pillow and bedding and using blackout shades in the bedroom.
Bedroom temperature, ambient light, diet and other aspects of day-to-day life can have strong impacts on sleep quality. The National Sleep Foundation recommends keeping your bedroom at a temperature of 60-67° F for more restorative sleep. Breaking out some extra blankets and turning the thermostat down to keep your body warm and your head cool is worth trying if you’ve been waking up groggy.
If you have limited control over your bedroom temperature, light level or background noise, there are some affordable products that can mitigate that. Cooling pillows, heated blankets, eye shades and white noise machines or small fans can all help optimize sleeping conditions. If you want to go the full nine yards, check out Broussard’s seven favorite sleep products at broussardlab.com/sleepkit.
Rather than only considering environmental factors, or treating insomnia as a medical condition, it can help to reassess our behaviors and attitudes about sleep through therapy, Rolle says.
“Cognitive behavioral therapy for insomnia is the gold standard treatment behind chronic insomnia,” she says, noting that studies have shown it to be more effective than medication. The treatment guides patients in understanding how their circadian rhythm functions, learning not to catastrophize if they’re sleeping poorly and implementing other behavioral and perceptual changes.
Rolle says we should also avoid “conditioned arousal” in bed, meaning we shouldn’t make a habit of working or worrying in bed. Lying awake at night worrying or tossing and turning in frustration conditions you to feel alert in bed. If you must work into the evening, your bed is a bad place to do it.
While sleep hygiene is important, it’s analogous to dental hygiene, Rolle says. If you already have a cavity, no amount of attention to dental hygiene is going to repair it. The same goes for sleep hygiene and insomnia.
“Insomnia usually starts out through a transition or a stressful time of your life,” she says. “It can also be certain medical things can set it off and, of course, mental health conditions are very bidirectional with sleep problems. Something sets this off, and it’s actually behaviors that really end up solidifying it.”
