What sleep deprivation does to your body—and your brain

I remember it so vividly. It had been a good morning with my kids—Sophie, then three, and Juliette, just a few months old—and I was showered, dressed and wearing makeup (an impressive feat for a mama with two littles, I thought). Soph had been a dream about sitting for breakfast and getting dressed, and Juliette had nursed well and was babbling happily.

I’ve totally got this, I thought, as I packed a diaper bag, zipped Sophie into her coat and buckled Juliette into her car seat for the drive to Soph’s daycare.

The part I wasn’t considering in this idyllic scene was the fact that I hadn’t slept for more than a two-hour stretch for months (and that’s if I was lucky!). My husband and I had moved Sophie to a “big-girl bed” a few months prior, in anticipation of our new arrival, and from the minute Sophie realized she had the freedom to leave her room, all bets were off. Cue hours-long bedtimes, musical beds and every stall tactic in the book. When we finally got her to sleep, she was up multiple times a night. No amount of strategizing worked to keep her snoozing until morning.

Then we added a newborn to the mix. Juliette started out as a solid sleeper. This time around, we had learned a lot more about infant sleep patterns. I held fast to the “sleep begets sleep” rule, and put her down for a nap every two hours like clockwork, knowing that if I let her get overtired, it would be a struggle to get her back on track. But by this particular morning, the nice sleep rhythm we’d settled into was shifting, and I wasn’t even getting the catnaps her schedule had previously afforded me. In short, I was beyond tired. But I was still functioning well—or so I thought—and I’d convinced myself that my body was simply getting used to the lack of sleep.

On the way to daycare, Sophie sang to the baby and chattered away at me as usual. After dropping her off, I headed back home with Juliette. It was a 30-minute trip, driving directly into the sun. The last thing I remember is glancing in the rear-view mirror to see Juliette sleeping in her car seat. Then, what seemed like a split-second later, a cacophony of noise startled me: I’d dozed off and drifted across three lanes of traffic. People were leaning on their horns and swerving to avoid me. It wasn’t until I hit the rumble strip that runs down the side of the highway that I was able to get my wits about me and stop the car. And then I burst into tears.

I was lucky—it could have been so much worse. No one was hurt, and we made it home OK. But until the accident, I hadn’t realized just how impaired by sleep deprivation I really was.

And the truly scary thing is, I know I’m not alone. There are legions of weary moms hiding behind their sunglasses as they push strollers and sustain themselves with caffeine all day. There are parents who have gone back to work, but their babies still aren’t sleeping through the night, so they’re trudging into the office and struggling to stay awake at their desks. We know we should go to bed earlier to compensate for the long, torturous night of interruptions ahead, but we still have too much to do after the kids’ bedtime: Switch the laundry. Make the lunches. Return that email. (And maybe do one fun or relaxing thing for ourselves? Ha.)

It's not just a first-year-of-parenthood phenomenon, either. A January 2019 study published by Oxford University Press (on behalf of the Sleep Research Society) found that for both moms and dads, sleep still hadn't returned to pre-pregnancy levels six years after having their first child.

Many parents don’t understand the negative effects of a lack of sleep, or of fragmented sleep, nor do they recognize how quickly physiological, cognitive and emotional functioning begin to suffer.

“Less than six hours of sleep in a single night is acute deprivation,” says Robyn Stremler, a registered nurse and associate professor at the Lawrence S. Bloomberg Faculty of Nursing at the University of Toronto, whose research focuses on sleep and parenting. “We know that human adults function best on seven to eight hours a night, and when you drop to less than six hours, for even one night, we start to see a decline in performance.” Chronic deprivation occurs when the lack of sleep is prolonged or persists for many nights, leading to continued or worsening impairment as time goes on.

Physical symptoms

Every parent of young kids has had someone say to them, “Whoa, you look tired.” When you glance in the mirror, you know what they’re talking about: It’s like a couple of years of parenting have aged you 10 years or more. Your face appears sallow, your skin isn’t as youthful and dewy as it used to be, and you could pack for a vacation with the dark bags under your eyes. According to Lisa Kellett, a dermatologist in Toronto, there is evidence that sleep deprivation and altered sleep patterns (such as working the night shift) ultimately result in decreased collagen production and the breakdown of skin elastins.

But your body is also reacting to the lack of sleep in many other, not so visible ways. For example, people who report chronically sleeping too little tend to have higher blood pressure, says Stremler.

“It can also affect the body’s hunger responses, so you make poor food choices more often. Your body thinks it wants more nutrient-dense foods, so you’ll reach for options with higher fat and sugar contents.” This means there is a relationship between a lack of sleep, a slower metabolism and weight gain, as well as fluctuations in your blood sugar levels.

Other physiological symptoms include blurred vision, dizziness, eye twitches and increased pain. You’re also three times more likely to catch a cold when sleep deprived, because the lack of shut-eye suppresses your immune system.

A 2011 study published in the medical journal Behavioral Sleep Medicine even found that a shortage of sleep can lead to what some have dubbed the “zombie effect” in parents, which is an impaired ability to demonstrate joy in your facial expressions. A similar study, published in 2013 in the journal Sleep, found that sleep deprivation can make you appear sadder or more morose to others, with swollen, redder eyes, hanging eyelids, darker under-eye circles, pale skin, more eye wrinkles and droopy corners of the mouth.

With symptoms like that, is it any wonder that tired parents aren’t feeling their best? You probably don’t have the energy or time to exercise, either, which compounds the sluggishness we feel from being under-slept and making unhealthy diet choices. We don’t need a scientific study to tell us our sex lives suffer as a side effect of sleep deprivation, too: Many new parents feel they have to choose between a few extra minutes of rest and devoting attention to their long-neglected relationship with their spouse.

Cognitive effects

When Conor Wild, a research associate at the Brain and Mind Institute at Western University, in London, Ont., found out he and his wife were expecting twins, he started to consider what two new bundles of joy would do to all facets of their life, including their sleep. This personal analysis spurred his recent research, which included a controlled survey of more than 10,000 respondents who reported on their sleep quality and duration before completing a series of cognitive tests.

Wild and his team discovered that getting too little sleep on a regular basis—less than seven or eight hours per night during the past month—is associated with a decline in mental acuity. Even a single night’s poor sleep can cause impairments, including declines in reasoning and problem solving, and in verbal abilities, such as understanding someone in conversation or comprehending written articles. (Interestingly, Wild and his team found that short-term memory was not impaired by too little sleep.)

Sleep deprivation and mental health

In addition to challenges in physiology and cognition, sleep deprivation can have grave consequences for mental health.

“Low mood can occur with even just one night of too little sleep, but for those who experience chronic deprivation, we see this issue compound over time,” says Stremler. “We also know there is a relationship between chronic lack of sleep and the development of diagnosable mental illnesses, like depression and anxiety.”

A parent’s emotional regulation and ability to cope is impaired when sleep is scarce, which means tired moms and dads are more likely to be irritable and easily frustrated (which, let’s be real, isn’t a good combo when young kids are involved). The next time you find yourself beyond exasperated over your two-year-old melting down about wearing socks or having to use the green dinner plate and not the blue one, consider your recent sleep pattern. You’re not going to have the same well of patience to deal with a difficult toddler, and you might notice you’re arguing more with your partner over things that seem like a big deal right now but are actually insignificant in the long run. Basic problem solving and daily tasks that would be straightforward on a full night’s rest can seem insurmountable when you’re exhausted. If you know you’re in the red on snooze time, take a breath, go easy on yourself (and others) and chalk it up to your ever-growing sleep deficit.

So what can you do?

Like me, many parents have convinced themselves that their bodies—and therefore their ability to function—have adjusted to the dearth of zzzs, but Stremler and Wild both say people just get used to the feeling of being so fatigued. That leads us to underestimate the effects on how we feel and how we perform. The best thing you can do for yourself is to add up the hours of sleep you’re getting (or not getting), admit that you actually do need to sleep, and figure out creative ways to remedy the situation.

“Moms and dads need to try to make sleep a priority,” says Stremler. “Parents are so busy and have so many things going on, but you have to recognize the importance of sleep and let a few things go. The extra amount of sleep will make a difference in how parents feel and function the next day.”

Of course, this is easier said than done when you’re dealing with small children and their ever-evolving sleep issues. I’d wager that logging more sleep is indeed already a priority for many exhausted parents—in fact, it may be all you think about when you’re up multiple times a night with a baby or toddler. But prioritizing sleep doesn’t mean you’re magically going to start getting unbroken chunks of quality, restorative sleep. It’s not as simple as “letting a few things go.” Believe me, if I knew the secret method for getting both kids to sleep through the night, every night, I would have done it by now. But I did ask the experts for tips on how my fellow mom-zombies (“mombies”) and I can eke out more pillow time.

1. Schedule sleep.

“If you have an erratic sleep schedule, like staying awake one night to get things done, it will be harder on subsequent nights to get good-quality sleep,” says Stremler. Staying up late interferes with your circadian rhythm, even if you try to go to bed early to make up for it the next night. Set a hard stop for when you need to be in bed every night and stick to it.

2. Squeeze in a nap.

“Claim back any sleep you can,” says Wild. If you’re a stay-at-home parent, consider actually sleeping when the baby sleeps (yup, we know, this means choosing sleep over showering, unloading the dishwasher or prepping dinner). If you do a morning “snooze feed” with the baby around 5 or 6 a.m., definitely go back to bed when the baby does. Parents with long work commutes on public transit could try to snooze while they ride. But don’t time a catnap too close to when you’re supposed to turn in for the night. You should aim for only 20 to 30 minutes; any longer, and you’ll get into the deeper stages of sleep (also known as REM sleep) and may end up with sleep inertia, that groggy feeling you might notice after a longer nap.

3. Negotiate shifts with your partner.

One of you takes the first half of the night to be on duty for kid wake-ups, while the other partner takes the second half. This means both parents will get longer stretches of uninterrupted sleep. You might need earplugs or somewhere quiet to sleep, away from any noise or kid commotion. (Families with the financial means could consider hiring a night nurse for shifts with a new baby, but that’s not a realistic solution for many.)

4. Stockpiling "catch-up sleep" doesn't work.

Sadly, an occasional 12-hour chunk of sleep isn’t going to fix the problem. Sleeping for too long is a thing too, and you won’t feel rested. Aim for a few subsequent nights of optimal timing—seven to eight hours—instead.

5. Know when you’re getting into sleep debt.

“There is good science showing that getting too little or no sleep on a regular basis is associated with many different kinds of impairments,” says Wild. When these deficits accumulate, it’s often referred to as “sleep debt,” and the larger the debt, the larger the impairment. Even if you don’t notice the damage accruing, note the amount of time you’ve slept in the past week or two and call for backup if you’re getting into dangerous territory.

My scary asleep-at-the-wheel moment was enough of a wake-up call (pun intended) to force a change in my habits. I began shifting my bedtime absurdly ahead, to 7:30 p.m., so I’d sleep for a while before my husband went to bed. Then I’d be on deck for any wake-ups in the wee hours. I also caught short naps whenever Juliette slept during the day. Her naps were never one- or two-hour stretches (I wish!), but I could almost always get 20 minutes. If I was too zonked to drive safely, I just called in tired to daycare and kept Sophie home, as hard as it was to juggle both kids.

Four years later, my girls still aren’t great sleepers, to be honest. We’ve tried different methods of sleep training, consulted sleep experts and tried any number of incentive and tracking systems. I inevitably wake up to a kid creepily standing at my bedside in the middle of the night or sharing my pillow most mornings. I can only hope my girls will eventually outgrow the sleep issues we’ve experienced. (Teenagers are supposed to sleep a lot, right? Right?!)

But in the meantime, I do know when my body has just had enough. At this point, I’ve also googled, “Can sleep deprivation shorten your life?” more times than I can count. (It totally does, in myriad ways: tripling your risk of type 2 diabetes, a 48 percent increase in developing heart disease and a 36 percent increased risk of colorectal cancer.) But I’d rather make more of an effort to go to bed extremely early than keep myself awake at night thinking about all of that, too.