You've probably heard of REM sleep — otherwise known as rapid eye movement sleep — at some point while troubleshooting your bedtime routine. If it sounds serious, that's because it is; it's a crucial period of the night where your heart quickens, breathing increases, and yes, your eyes flutter around rapidly. It's likely when you have your most life-like dreams, but more importantly, sleep specialists have years of data that suggests REM sleep is when your brain stores short-term memories from days prior into your long-term bank. Research also shows that REM sleep is tied to your cognitive health, including learning abilities and mood regulation, among other abilities.
You'd probably guess that the more REM sleep you enjoy, the sharper your brain will be, right? Sadly, it's not as simple as that. Your body needs to get through most of the night before it enjoys a cognitive boost in a REM sleep period. REM is usually the last long period of sleep after three other stages that are part of a perfect night's sleep: stages one through three of what experts call NREM sleep, or non-rapid eye movement cycles.
It's not that REM is the only time your brain is at work, either, as NREM stages N1, N2, and N3 are known to support reasoning, retention, and memory skills all respectively, says Kent Smith, DDS, D-ABDSM, president of the American Sleep & Breathing Academy and the founding director of Sleep Dallas. Every stage lasts about 90 minutes or more, but non-REM sleep often takes up the first 70-75% of your total sleep time, and your body won't skip over these stages to reach a REM state first — each cycle usually repeats up to three or four times a night as well.
"[REM sleep] is when the brain activities pick up, you have vivid dreams and the body experiences temporary paralysis of the muscles," Smith adds. "It's vital for restoring the mind and helping the brain deal with emotional information. If a person doesn't obtain adequate sleep, and subsequent REM sleep, it can have a negative impact on one's thinking during the day, their emotions, and overall physical health and quality of life."
Since REM sleep occurs naturally, you'll need to practice good sleep hygiene to allow yourself to reach a REM stage at night all of your own. Below, experts share what you need to know about REM cycles, why you can't 'hack' your way to REM sleep, and how much REM sleep you really need to feel your best.
Why is REM sleep important?
Earlier in the night, your body is doing its best to calm itself and restore both your physical and mental stamina, and REM sleep may occur in short bursts in the first few hours after you've passed out. Usually, Smith adds, most adults can experience anywhere from three to five REM cycles in any given evening, and they become longer as the night progresses into the early morning.
REM cycles can be easily impacted if you aren't getting enough sleep, or if you're disrupting or influencing your sleep cycles through non-prescribed pharmaceuticals or chronic alcohol use prior to bedtime. Alcibiades Rodriguez, M.D., a sleep medicine specialist and the medical director of NYU Langone's Comprehensive Epilepsy and Sleep Center, explains that REM sleep periods (or a lack thereof) play a huge role in why sleepless people experience a myriad of physical and mental issues over time.
Both experts agree that not getting enough sleep, and thus not fully enjoying multiple REM cycles, can lead to a higher risk of cardiovascular disease, diabetes, dementia, and depression, among other sleep-related issues like chronic sleep apnea or insomnia.
Is REM sleep different from deep sleep?
Deep sleep is actually associated with the period of sleep known as stage N3, Dr. Rodriguez explains, and not directly with REM sleep (known as the final fourth stage of sleep). Deep sleep occurs usually before REM sleep but long after you've first fallen asleep; at this point, your body has relaxed and your brain patterns have entirely changed since you were awake, he adds.
Remember, your body naturally courses through these cycles on repeat every night, usually three or four times before you wake up.
Here's a brief overview of each sleep cycle that occurs throughout the night:
NREM Stage N1: This is when you fall asleep, and this period is very short, as it involves you dozing off and generally winding down a bunch of physical and mental functions. It can last anywhere from 10 to 20 minutes, and you can be jolted awake easily if there's activity occurring around you.
NREM Stage N2: This period of sleep takes up about 50% of your entire sleep duration throughout the night, Smith says. Muscles have relaxed at this point, your body temperature drops a bit, and the brain begins to produce what's known as "slow waves" (or Delta waves) at this time, Dr. Rodriguez adds.
NREM Stage N3: This stage is what people refer to as "deep sleep" and brain activity increases, leading to some loose body movements as well as slow breathing and pulse. "This is a critical stage for body recovery and growth," Smith explains.
REM Sleep: This sleep is indeed so deep, almost all of your muscles are unregulated, your breathing is irregular, and dreams begin.
How much REM sleep do you need?
Infants and young children will spend more time doing so, but adults usually spend more time in non-REM sleep cycles, which is natural. Sleep specialists usually calculate a person's REM activity in percentages, Dr. Rodriguez says, and that most adults should spend at least 20% of their time sleeping in a REM stage.
Each age group has different recommended sleep totals that they should reach for on a nightly basis. A healthy standard for adults, according to the National Sleep Foundation, is between seven and nine hours of sleep each night. If you're asleep for eight hours on average, then, 20% works out to be around 1.6 hours — or 96 minutes, to be exact.
How to increase REM sleep naturally:
Because our bodies naturally cycle through different sleep periods, and REM sleep often occurs last (after getting to bed at a reasonable hour!), experts say you don't have to worry about getting REM sleep directly.
It's more about supercharging your sleep routine to ensure you're doing your best to enjoy a good night's sleep overall, experts agree. We've previously shared some of the best habits to pick up for a good night's sleep, as well as helpful tools and products to make going to bed that much easier. Below, we're recapping some of the ways in which you can improve your sleep routine right now:
Try sticking to a consistent wake-up time. Yes, even on the weekends. "Although it can be tempting to go to bed later and sleep in on the weekends, research shows that doing so is actually associated with a worse mood, higher risk of heart disease, and overall a decline in health," Smith says.
Choose the right bedtime snacks. Sometimes, a favorite snack can be working against you if you eat up against your bedtime, especially spicy foods or sugary items. Try to eat a snack that can actually aid your body in naturally drifting off to sleep.
Avoid alcohol and recreational drugs before bed. Alcohol and many kinds of drugs act as natural depressants on your nervous system and can inhibit some of the bodily functions that naturally occur during one of the sleep cycles discussed above.
Hit the lights. Dimming the lights (or turning them off completely) at least one hour before you want to fall asleep can help signal to your internal clock (which also regulates your mood!) that it's bedtime. Light can suppress your body's melatonin hormone production, Smith adds, so it's crucial to keep lights dimmed in your sleeping space.
Leave electronics outside your bedroom. Since they all emit light, phones, computers, and televisions should be turned off in the hour leading up to your bedtime. Blue light may impact your sleep hormones just as much as other sources of light, so this is a tough habit you'll need to practice breaking. "Start by eliminating electronics 15 minutes before bed, then 30 minutes, then one hour before bed over time," Smith says.
Don't lie awake: "If you find yourself anxious and unable to find the right mindset to sleep, get out of bed," Smith advises. "If you're unable to fall asleep within 10 to 20 minutes, move to another room and do something that relaxes you, like reading or meditation."
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