It's Sleep Awareness Week from March 8 to March 14, and Allure is talking all things rest, from what happens when we don't get enough to how to make the most out of our time between the sheets.
While the average adult typically needs between seven and nine hours of sleep per night, many of us aren’t getting that much on a regular basis. According to a survey published in 2018 in the academic journal Sleep, close to a third of American adults get fewer than six hours of sleep a night, which can result in what experts call sleep debt.
Think of sleep as a currency. Sleeping the necessary seven to nine hours is like saving, and any deprivation (or, being awake more than 17 hours in a row) is like spending. If you spend too much, you could go into sleep debt, which essentially means you owe yourself some rest.
“Sleep debt is a term used if you accumulate lack of sleep below that needed seven to nine hours each night,” says Seth Rinderknecht, a family medicine doctor at Eskenazi Health in Indianapolis. “For example, if you’re getting six hours of sleep and you need eight, within a week you can create a sleep debt of 14 hours.”
Whether you’re losing sleep due to a busy schedule or a medical condition, it’s possible (and recommended) to make up for all those lost hours — but paying back your sleep debt isn’t as simple as sleeping an extra few hours on the weekend.
What are the effects of sleep debt?
Lack of sleep can leave you feeling run-down the next day, but there’s more to the sleep deprivation issue. Rafael Pelayo, a sleep specialist at the Stanford Sleep Medicine Center, says sleep restores the body by cleansing the brain of toxins with cerebrospinal fluid. Plus, when you’re asleep, your whole body rests — even your kidneys make less urine. So when you’re not getting enough sleep, you’re cutting yourself short on these restorative processes.
For short durations, however, most of us can survive without ample sleep. That’s why we can survive jet lag or getting up every two hours to care for a hungry baby or pet. “Our brains are built to push off sleep…we can do without sleep in certain circumstances without falling apart,” he says. “If you skip sleep for a night, you will feel it, but you can still more or less function to some degree.”
But that kind of sleep deprivation isn’t sustainable. Long-term sleep debt can have literally ill effects, according to Rinderknecht. Research on sleep deprivation shows long-term sleep debt can lead to conditions like insulin resistance and heart disease; another study found fragmented sleep can lead to the acceleration of cancer growth.
Long-term sleep debt may also contribute to chronic medical conditions like hypertension, heart disease, diabetes, memory loss, cardiovascular disease, and an increased risk for stroke. “It’s more than just irritability and tiredness,” explains Rinderknecht. “Chronic sleep deprivation can increase your risk for serious, life-threatening medical problems.”
Is it possible to catch up on the sleep you’ve missed?
To prevent the effects of sleep deprivation on the body and improve overall well-being, Pelayo says it’s important to prioritize sleep like you might, say, eating nutritious food. But research shows it’s not as simple as “repaying” the sleep you lost during the week by sleeping in on the weekend.
Alon Avidan, a professor and the vice chair of neurology at the UCLA David Geffen School of Medicine and director of the UCLA Sleep Disorders Center, describes sleep debt as borrowing at a high interest rate. You’ll need to pay more — and be strategic — to make up for all those lost hours.
“The ability of one to make up for [sleep deprivation] by sleeping in later isn’t a direct proportion,” says Avidan. “For one hour of sleep deprivation, you need a full night of proper sleep for recovery.” So if you sleep four hours less than you need on a weeknight, you would need about four nights of the recommended seven to nine hours to make up for it.
For those with more excessive sleep debt — for example, a parent who is short on sleep for several years — the make-up will be more extensive, and could take a few months, Lawrence J. Epstein, medical director of the Harvard-affiliated Sleep HealthCenters, tells Scientific American.
As you work on repaying your sleep debt, focus more on a habit of night-time sleep. When you’re running on low sleep, it may seem like a smart idea to sneak off for a nap during the day — especially if you’re struggling to stay awake. But the key to repaying sleep debt, Rinderknecht says, is sleeping for seven to nine continuous hours, multiple nights in a row, so you can experience all the sleep phases you need to restore your body. “Getting that deep, non-REM sleep is really the restorative sleep that benefits patients from a health standpoint,” he says.
Taking a long nap, especially if it’s too late in the day, can actually disrupt your sleep cycle and keep you from those continuous hours of sleep you need. If you absolutely can’t keep your eyes open, or you’re chronically sleep-deprived, Avidan recommends a quick, 15- to 20-minute power nap between 1 and 3 pm, then going to bed at your regular time. “We often see people who are sleeping in and taking a nap for two hours and then when they try to sleep they can’t because their drive for sleep is partially restored by that power nap,” he says.
How can people practice better sleep habits?
It’s definitely possible — albeit a little difficult — to counter the effects of sleep deprivation. Rinderknecht says getting the seven to nine hours you need each night is a far better way to maintain healthy sleep habits than trying to make up for it later on. To improve your habits so you don’t go into sleep debt, Rinderknecht recommends basic “sleep hygiene” practices. The first thing to focus on is attempting to keep a regular sleep schedule. “Our bodies work on a circadian rhythm, so to work with your body, go to bed at a similar time each night,” he says.
When you go to sleep, give your body cues to rest by cozying up in a dark, quiet room. Avidan suggests keeping your thermostat set to 65 to 67 degrees when possible, since cooler temperatures can help the body release melatonin, which promotes sleep.
Another important factor in sleep hygiene: Keeping technology out of the bedroom. Because blue-light released from phone, TV, and computer screens has been shown to disrupt the circadian rhythm, it’s best to put your devices down two or three hours before you plan to go to bed.
What you eat and drink can also play a role in how well you sleep. Rinderknecht suggests avoiding sugary foods and drinks, along with caffeine, at night time. It’s also best to avoid using alcohol as a sleep aid. Though a glass of wine before bed might make you sleepy, Rinderknecht says drinking actually results in “sleep fragmentation,” which means you’ll get less restful sleep and may potentially wake up earlier. And while exercise can be beneficial in promoting good sleep in general, don’t work out too hard before bedtime — your body releases endorphins when you work out, which he says don’t create an environment conducive to sleep.
If you’ve adjusted your lifestyle but you’re still not sleeping well, Avidan says it’s important to rule out underlying medical conditions like sleep apnea or restless leg syndrome, both of which can impact sleep quality and quantity. Talk to your doctor about your concerns so you can come up with a plan for sleeping — and feeling — better. “We want people to make sleep a priority,” says Pelayo. “You can get by with less sleep, but that doesn’t mean you’re at your best.”
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