Guide To The 4 Stages Of Sleep

You probably have your personal preferences and rituals for going to sleep but did you know that everyone goes through similar sleep cycles? These cycles can determine just how rested we feel, as well as influence our overall health.

If you’ve ever spent time in bed only to feel that you didn’t get “good sleep,” you’ll want to read through this guide to sleep cycles and stages to better understand how sleep works and what you can do to make it the best rest ever.

What Is the Sleep Cycle?

While it may feel like you close your eyes and have the same type of sleep all night long, your sleep is broken up into different stages that cycle over and over through your sleep session. How many cycles you go through depends on many factors, but most people typically enter the four different sleep stages at least a few times a night, with each cycle lasting around 90 minutes.

Not only do sleep cycles vary from person to person, but they also vary for the same person. The sleep cycle you get at the beginning of the night is likely much shorter than the last cycle you enter before waking up. Time spent in each of the four sleep stages also changes from cycle to cycle.

Things that affect your time spent in sleep stages, the length of your sleep cycles, and the number of sleep cycles include age, health, lifestyle, and whether you used any medications or alcohol before falling asleep.

What Are the Sleep Stages?

Four sleep stages happen in a sleep cycle, including the NREM stages of N1, N2, and N3, which are the hardest to wake someone from. The sleep cycle also includes the Rapid Eye Movement (REM) stage, which happens near the end. Each plays a different role in helping you rest and restore your body so that you’re ready to go the next day.

Stage 1 (N1)

When you’re just settling down for sleep and still dozing off, you’re in the N1 stage of sleep. It’s a short sleep stage, lasting just a few minutes. You may find yourself twitching or randomly thinking of things during this stage since your body hasn’t completely “shut off” for the night.

Someone in the N1 stage isn't hard to wake, but since it's so short, most people can easily move into the next stage if they aren't disturbed.

Stage 2 (N2)

Your body relaxes even more in this next stage, making up around half of your sleep time each evening. Your breathing and heart rate slow, and your temperature drops slightly. The brain also slows down but experiences short, active surges that may play a role in keeping you from being woken up during this stage.

Your eye movement ceases during this stage. The N2 phase can last between 10 and 25 minutes, getting longer each time you enter it during the night. 

Stage 3 (N3)

Stage 3, or "deep sleep," is the stage scientists believe does the most to restore your body. It's also the hardest to get someone to come out of as you relax and slow down even further than in previous stages.

The first half of the night is when we tend to get the most N3 sleep, with each 20-40 minutes session getting shorter as the night continues. Brain waves also change during this time, giving this stage the alternate names of “slow-wave sleep (SWS)” or “delta sleep.”

REM Sleep

Most people are familiar with REM sleep (the Rapid-Eye Movement stage), which makes you unable to move most parts of your body except the eyes and muscles used to breathe. If you watch someone in the REM stage sleep, you can see their eyes moving rapidly behind their eyelids, which is how this stage got its name.

Most dreams occur in the REM stage, although they can happen anytime. REM typically happens after you've been asleep awhile, which is why you don't usually enter REM stage sleep if you take a quick nap during the day. REM stages get longer as the night goes on, making up around a quarter of the time spent asleep.

How Much Sleep Do You Need?

You’ve likely heard the advice to get “8 hours of sleep,” but this is a one-size-fits-all piece of advice that may not apply to you. The Centers for Disease Control (CDC) developed their sleep recommendations chart based on age, so you won’t find a newborn needing the same amount of sleep as a senior adult, for example.

If you follow the guidelines and find you are still very tired or not well-rested, you may need more. Sickness, certain medications, and periods of intense activity may require you to get more sleep than you realize.

You can determine how much sleep you need, when you should go to bed, and when you should wake up by using our sleep calculator.

Factors That Affect The Sleep Stages

Most of us don’t sleep in a vacuum, and we will be affected by outside and internal factors as we try to fall (and stay) asleep. Some of these things we can control, but others will be things we just have to deal with.

Age

We can’t do anything about our age, which can play a big role in the quality and amount of sleep we get each night. Our age determines how much sleep we need, affecting the overall length of our sleep cycles and the stages within them.

Age can also affect how hard it is to sleep. Babies who need to eat frequently may struggle to fall asleep, only to grow into children with very restful nights. Then, as we grow up, the factors that adults deal with (such as caffeine, stress, or pain) can again make it difficult to sleep.

Changes in our bodies as we age, including hormonal shifts, can make sleeping easier or harder.

According to the Division of Sleep Medicine at Harvard Medical School, sleep cycles range from 50 minutes in kids to 90 minutes in adults, with children’s sleep cycles containing large chunks of N3 sleep. Older senior adults get very little of this N3 sleep, resulting in lighter and shorter sleep sessions that may make it hard to stay asleep through the night.

Medications

You only have to read the documentation that comes with a prescription or over-the-counter (OTC) medicine to see that medications can affect people in various ways. Some medications, such as antihistamines, can make people sleepy, while others act as stimulants that may make it hard to fall asleep at night.

Some medications are marked clearly by pharmaceutical companies with warnings about how they affect sleep, while others may require you to do some research. Asking a pharmacist about new medications, even if purchased over the counter, is always a good idea. They can provide tips for the best time to take medicine to keep them from interfering with rest.

Caffeine

The link between caffeine and sleep is well documented, with scientists finding that caffeine typically “prolonged sleep latency, reduced total sleep time and sleep efficiency, and worsened perceived sleep quality.”

Older adults may be more sensitive to caffeine than younger adults, but caffeine may also affect people differently based on genetics. If someone is having difficulty sleeping and frequently consumes caffeine in the afternoon or evening, it may be worth giving up caffeine (at least later in the day) to see if it makes a positive difference in getting better sleep.

Sleep Disorders

A sleep disorder is defined as any condition that affects sleep, with the National Institutes of Health counting over 80 different sleep disorders. They include insomnia, sleep apnea, restless leg syndrome, shift work disorder, and narcolepsy. These disorders may make it hard to fall asleep, stay asleep, get quality sleep, or even keep from falling asleep at the appropriate time.

Some sleep disorders may be treated so they don’t occur or at least lessen. Others may not be treated but simply dealt with.

If you suspect you have a sleep disorder, talking to a doctor or a licensed sleep consultant may get you a treatment plan that works for your unique situation.

Stress and Mental Health Conditions

Sleep and anxiety don’t go well together, with this condition causing acid reflux, increased heart rate and breathing, and racing thoughts. It’s just one of the culprits, as depression and other mental health conditions also affect your sleep quality. Not only do these conditions make it difficult to fall asleep, but the medications prescribed to treat them can also cause sleeplessness. Harvard Medical School found that antidepressants can disrupt REM cycles.

Whether it's temporary stress, like worrying about a test the night before, or a long-term anxiety disorder, the result is a change in sleep stages and cycles that can lead to less restful sleep over time.

Naps

Unless you didn't get much sleep last night (or you are an infant), taking a midday nap can mess up your sleep patterns. Too long of a nap at the wrong time of day can confuse your body and its circadian rhythms.

Unless you cannot hold out until bedtime, you should carefully plan naps to not interfere with sleep.

Diet

Some foods, such as bananas or a glass of milk, may be linked to better sleep. More important than trying foods that help you sleep is to avoid those that prevent it. If you suffer from heartburn or gastric problems, skip fried foods, chocolate, or alcohol.

It may take some time to figure out what foods affect your sleep. Keeping a food journal can help you document the things you eat so you can find a connection to your sleep problems.

Room Temperature

What’s the best temperature to fall asleep? Experts recommend 68 degrees as the place to set your thermostat, with studies showing that too hot of a temperature can disrupt essential sleep stages. This temperature is likely much cooler than you have in your house during the winter months, but you can always bring a few blankets to bed and enjoy the benefits of a cooler room temp.

Tips To Get Deeper Sleep

How long you can go without sleep depends on your situation, but it’s best not to try to short yourself on sleep. Your body needs it to recharge and repair itself. Not sleeping enough can lead to health issues and make it harder for you to complete regular tasks.

To get better sleep, consider making your room a comfortable sanctuary free of noise, light, and stressful factors. Try not to take work or other tasks to bed. That way, you're not associating the place you sleep with stress.

Deal with any annoyances immediately, whether fixing a squeaky bed or upgrading your worn-out mattress entirely.

Avoid foods, medications, or drinks that act as stimulants, and be careful with any sleep aids marketed as an easy hack for sleepless nights.

Sleep Stages FAQ

Each stage of your sleep cycle has a distinct purpose, which is essential for overall health and well-being.

What stage of sleep do dreams occur in?

Dreams can occur in any stage but are most likely to happen in the Rapid-Eye Movement (REM) stage. In this stage, your mind can be most creative and carefree, and you are harder to wake up. These two conditions make it the ideal time to have some imaginative dreams.

What dietary changes should I make to get better sleep?

Several foods can help you sleep better, including bananas, walnuts, and kale. Good overall nutrition may be more important than eating any food; however, a lack of essential nutrients, vitamins, and minerals can wreak havoc on your sleep cycle.