CUriosity: What does an all-nighter do to your body?
In CUriosity, experts across the CU Boulder campus answer pressing questions about humans, our planet and the universe beyond.
This week, Integrative Physiology Professor Ken Wright, answers: “What does an all-nighter do to your body?”
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Whether we’re cramming for finals, catching a red-eye flight, binge-watching rom-coms, or indulging in a bit too much cheer, the holiday season can wreak havoc on sleep.
Surveys suggest that of U.S. adults stay up all night at least once during the year, and report pulling an all-nighter monthly. But can just one night of missed sleep really hurt us?
“Absolutely,” said Integrative Physiology Professor Ken Wright, director of the Sleep and Chronobiology Laboratory at CU Boulder. “Pulling an all-nighter is a significant stressor, both physiologically and cognitively, to the body.”
Over the past two decades, Wright has invited countless paid volunteers into his lab for days-long, tightly controlled experiments. In in their 20s, he found that staying up all night and sleeping all day just once disrupted the levels and timing of 129 key proteins circulating in the blood, including those that regulate appetite and energy, keep blood sugar in check and fend off illness.
Exposure to light when the body is accustomed to darkness can also throw off the timing of hormones, including melatonin (which, among other things, signals our body that it’s time to rest) and cortisol (the “stress hormone”). These shifts can disrupt our body clock, or circadian rhythm, making it harder to sleep when we want to.
Eating at a time when our body is not ready to process food can promote weight gain and boost Type-II diabetes risk—as studies show we store more calories as fat and are less efficient at turning sugar into energy at night.
Ken Wright
“A calorie is not just a calorie. If you eat junk food in the middle of the night, it can be even worse for you than eating that same junk food during the day,” said Wright.
The immune system also stands down, even when we are awake, during our “biological night” (a time when our body is conditioned to rest and recover and is not typically exposed to pathogens.) This makes us more vulnerable to injury and illness if they hit us in the wee hours of morning.
For instance, one study by another research team found that humans heal 60% faster when they sustain wounds during the day than at night. to viruses when they were supposed to be resting, those pathogens replicated 10 times faster than in mice infected during waking hours.
“Timing matters,” said Wright. “If you are awake in the middle of the night and you’re exposed to someone who is sick, you have an increased risk of getting sick.”
Lack of sleep can also do a number on our thinking the next day, with that skipping a night’s sleep is about the same as having a 0.08 blood alcohol level.
“If you drive after staying up all night, it is the equivalent of driving drunk,” Wright warned.
The sleep scientist has some advice for students cramming for finals: Don’t wait until the night before your test and stay up studying until dawn. Instead, study days prior to a test and review your notes right before bed because sleep can help consolidate your memories. If you do have to stay up late, make sure your midnight snack is as healthy as possible and avoid driving the next day.
Your body will thank you, and your grades might, too.