Why Are the Sleep Stages Important?

Woman Sleeping
Illustration: Catalina Williams
Jan 31, 2022

There’s a reason people advise you ‘sleep on it’ ahead of making an important decision. Sleep is essential for your brain to function properly. It’s not a stretch to say that poor sleep hygiene could impact your overall mental and physical health — and even hunger and fertility. 

But that doesn’t mean people always put themselves in a position to get great sleep. Enter: bright screens, afternoon coffees, and late nights out. So we talked to health psychologist and sleep coach Dr. Julia Kogan about why sleep is so important for your overall health, what the four sleep stages are (and why you need to hit all of them), and what it takes to actually feel well-rested.

So sleep really is that important, huh?

You know it is. The fact is that depression and sleep problems often go hand in hand, with depression making it hard to sleep, and then lack of sleep making depression worse. A number of sleep issues are associated with depression, like insomnia (when you have persistent difficulty falling asleep or getting quality sleep) and obstructive sleep apnea (when you have trouble breathing while you sleep). And when it comes to physical health, getting inadequate sleep can put the body more at risk for cardiovascular disease and diabetes. It can even affect the production of hormones, impacting things like fertility and food cravings. See: the follicle-stimulating hormone, which regulates your period and helps you to get pregnant. And the hormones ghrelin and leptin, which regulate your appetite and tell the body when it feels hungry and full.

Sleep stages: Remind me what those are.

You probably know about REM (rapid eye movement). And then there are the non-REM sleep stages: N1, N2, and N3. Each serves a unique function for your body and brain. If you get the recommended seven to nine hours of sleep, you should be able to hit all stages multiple times a night. But not getting enough quality rest can do some damage. 

  • N1… Why you need it: to transition into sleep. Here, you begin the process of slowing down your breathing and relaxing your muscles. TTK: When you’re starting to fall asleep and you twitch, that’s called a hypnic jerk. It tends to happen during N1 — and is usually NBD. 

  • N2… Why you need it: to slow down your body temperature and heart rate for deep sleep. You spend the most time asleep in this stage. TTK: sleep spindles. That's a term for the brief bursts of neural activity during N2 that likely help consolidate memories. 

  • N3… Why you need it: so your body can physically heal. Think: repairing tissue, regenerating cells, and fighting sickness. Aka beauty sleep. This is the stage when you get the deepest sleep, which is essential for feeling energetic the next day. TTK: N3 can also be called “delta sleep” because it’s when your brain increases the production of delta waves, which make for a deeper state of relaxation.

  • REM... Why you need it: there’s a good chance you’re processing emotions and storing memories in this stage. In other words, this is the sleep they talk about when they suggest you ‘sleep on it’ to solve a problem. It's when your brain is most active and you do most of your dreaming. But the muscles in your limbs are temporarily paralyzed — so you don’t act out your dreams. TTK: If you feel like you don’t remember most of your dreams, there’s a reason for that. Research suggests that certain neurons fired during REM may help your brain actively forget new information. Basically, to save space for the important stuff. 

So how do I get lots of ‘deep sleep’?

The key is to have good sleep hygiene so that you can actually get quality sleep while you’re in bed. Dr. Kogan has these tips for getting an A+ on your Zzz’s…

  • Make sure your bed is for sleep (or sexual activity) only…Working from bed, watching TV in bed, eating in bed, scrolling through your phone in bed — they’re all no-nos. “Basically anything that you're doing in bed that's not sleeping teaches your brain over time that this bed is a place of activity,” says Dr. Kogan. That leads to “conditioned insomnia”: when ‘going to bed’ makes you feel more awake than tired.

  • Don’t get into bed until you're actually sleepy…It’s great to *want to* go to bed at 10 p.m. But if you’re not sleepy by then, you won’t fall asleep. You’ll toss, you’ll turn, and you’ll make it harder for your body to connect the idea of “bed” with “snooze central." 

  • Get your body ready for bed...In order to get into that desired tired state, you need to give yourself at least 15 to 30 minutes to wind down. That means powering off your electronics (you can do it), practicing some deep breathing, and trying what’s called progressive muscle relaxation. That’s when you create tension in parts of your body and then release it, like shrugging and squeezing back your shoulders before gently dropping them. Dr. Kogan says the process is good for combating stress because it “teaches the body to know the difference between tension and relaxation, by creating a little bit of tension and then practicing being fully relaxed.” Meditation and mindfulness apps could also help. 

What can get in the way of good sleep?

A lot. Studies show that about a third of adults have chronic insomnia. Yes, you read that right. And women tend to deal with more sleep challenges than men. Ambitious women, in particular, can wind up skimping on sleep because “there's this perception that sacrificing sleep can help us be more productive,” says Dr. Kogan, whose clients are mostly millennial women. Other contributors to poor sleep hygiene include...

  • Caffeine…Studies show that drinking coffee four to six hours before bedtime could limit your time in the delta wave sleep stages. A little science as to why: as caffeine metabolizes, it blocks the receptors in your brain that are supposed to get the sleep-promoting compound adenosine. PSA: many teas and chocolate also contain caffeine. 

  • Alcohol…Wine not? You ask. Because although it can put you to bed quicker, it could suppress your rapid eye movement and keep you from hitting deep sleep. And later on your sleep might get interrupted by the 10 times you wake up to pee (reminder: alcohol’s a diuretic). One tip: Wait two to three hours after drinking before you go to bed, says Dr. Kogan. Still, multiple drinks in one night will likely hurt your sleep.

  • Medication…Some prescriptions and over-the-counter meds can interfere with sleep. Chemicals impact everyone differently, but everything from antidepressants to asthma and heart medications can interfere with sleep quality. Speaking of medication, Dr. Kogan rarely recommends taking sleep aids like melatonin. She says they can lead to a certain level of dependency if used in certain ways. And that the cause of insomnia usually has to do with an underlying concern like stress, which should be the issue that’s addressed first. 

  • Sleep disorders…There are dozens. But some of the major types we haven’t mentioned include restless leg syndrome (like it sounds: when you feel like you need to move your legs), circadian rhythm disorders (like jet lag but for longer), and narcolepsy (when you can’t stay awake during the day). Genetics, mental conditions, pain, and medicines can all be factors. If you think you’re dealing with a sleep disorder, schedule a visit with your PCP. And then consider talking with a therapist who focuses on sleep issues (like Dr. Kogan) or another provider who specializes in sleep medicine. 


No more saying 'I’ll sleep when I’m dead.' Because you need adequate sleep to stay alive and well. And that means practicing good sleep habits, like making sure your bed is a sacred space that you only enter when you’re sleepy. #HustleCulture should really be about hustling to get to bed so that you can hit alllll of the sleep stages. Then you can wake up refreshed and ready to tackle the day.

This content is for informational and educational purposes only. It does not constitute a medical opinion, medical advice, or diagnosis or treatment of any particular condition. 

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