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What Happens When You Sleep?

Sleep-Explained-1

 
Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.

 
 
Why do We Need Sleep? | What are the Stages of Sleep? | How to Improve Sleep

 

Overview

The average person spends around one-third of their life sleeping or trying to sleep. That’s a significant amount of your life spent with your eyes shut. 

Many people try to find ways to stay up late to get more things done, but what about the things your body gets done during sleep? Figuring out what goes on with your body while you’re not awake helps you understand the importance of sleep. 

A healthy adult needs about 7-9 hours of sleep each night.[1] During those sleeping hours, both your body and brain get the rest they need and prep for the waking hours to come. 

This article will help you break down sleep, why it is essential, what happens in a sleep cycle, things that happen to your brain and body while you sleep, and how to sleep better. 

 

Why do we Need Sleep?

“I didn’t sleep well last night” is a common answer you’d get when you ask someone why they look tired or are in a bad mood. 

Getting enough shut-eye is very important for staying both mentally and physically healthy. That’s why the CDC declared insufficient sleep as a public health problem.[2]

When you go to bed, your mind and body rest, you de-stress, and save up on energy. Sleep also promotes growth, healing, and boosts your immunity. For this reason, sleep deprivation increases your risk for certain diseases and can harm you mentally.[3]

Your sleep cycle has stages that change through the night. The quality of your sleep depends on what happens during the different sleep stages.

 

What are the Stages of Sleep?

During the night, you go through 3-5 cycles of sleep.[4] Each cycle consists of two phases: non-REM (non-rapid eye movement) sleep and REM (rapid eye movement) sleep. 

Non-REM happens first and is divided into three stages, followed by one REM sleep stage. 

Scofa-Sleep-Explained-2

Non-REM Sleep:

Non-REM sleep is the deep sleep that is harder to wake up from and lasts 1-2 hours. The three stages of non-REM sleep are:

 

Stage 1 (NREM N1): 

The first stage of sleep consists of those 5-10 minutes as you begin to fall asleep:

  • Your eyelids and muscles begin to feel heavier
  • You start slowly drifting during this stage of light sleep
  • You’re easy to wake during N1

 

Stage 2 (NREM N2): 

During the second stage, which lasts for 30-60 minutes:

  • Your body gets ready to enter deep sleep
  • Your muscles alternatively contract and relax
  • Your heart rate slows down
  • Your body temperature drops

 

Stage 3 (NREM N3):

 This stage is deep sleep and lasts about 20-40 minutes: 

  • It’s referred to as delta sleep or slow-wave stage
  • You begin to experience delta brain waves (very slow brain waves)
  • You’re hard to wake up during stage 3 of NREM
  • Your eye movement and muscle activity are minimal

 

REM Sleep:

During rapid eye movement sleep:

  • Sleep is not as deep as non-REM
  • Brain activity increases, causing vivid dreams
  • Muscles are paralyzed, so you can’t move your arms or legs
  • Breathing quickens
  • Heart rate and blood pressure increase

The REM stage lasts for around 10 minutes during the first sleep cycle. The rapid eye movement stage starts lasting longer with every sleep cycle. 

 

What Happens to Your Body and Brain?

While you’re getting the sleep you need, your body releases growth hormones and proteins. A good night’s sleep promotes muscle and bone growth, tissue repair, and robust immunity. 

Not getting enough sleep can shorten your lifespan and increase your risk for diabetes, obesity, and heart problems.[5]

While awake, sometimes you can’t stop yourself from overthinking your daily problems and stresses, taking a toll on your psyche. 

Sleeping gives you a temporary break from that and enhances your mood the next day. Sleep also helps repair your nerve cells and their functions, strengthen your brain, and restore abilities. Quality sleep enhances your memory, thinking ability, and ability to concentrate.[3]

 

How to Improve Sleep

Good sleeping habits can help improve the quality of your sleep. Here are some tips you can follow for better sleep:

 

1) Create a Sleep Routine

Try to go to bed and wake up at around the same time each day. This sleep schedule will keep both your body and mind well-rested.

If it’s taking you too long to fall asleep, try to do something relaxing like listen to music or read before bed.

 

2) Avoid Alcohol and Caffeine before Bedtime

Try not to consume caffeine and alcohol close to your bedtime as they make it harder for you to fall asleep, or they can interrupt your sleep cycle. 

 

3) Keep your Room Sleep-Friendly

Create a sleep-friendly environment in your sleeping space. Regulate your room’s temperature, access to light, and noise isolation.

 

4) Minimize your use of electronics before bed

Melatonin is a hormone that is important for sleep. The blue light emitted from your phone or tablet screen interferes with melatonin production, leading to sleep disturbances. 

 

5) Watch What you Eat

Lack of sleep is tied to the levels of two appetite-related hormones called Ghrelin, and Leptin.[6] These hormones are related to feelings of hunger and fullness.

That’s why going to bed too hungry or too full can keep you up late. So try to avoid heavy meals later in the day.

 

Seek Medical Attention 

It’s not uncommon to have a sleepless night now and then; however, if you feel that you’re not getting enough sleep or suffer from a sleep disorder, find a sleep specialist.

Having trouble sleeping for a long time can cause severe mental and physical problems. When sleeping issues are diagnosed and treated by a sleep doctor, you’ll feel healthier and happier. 

 

References:

  1. Watson NF, Badr MS, Belenky G, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-844. doi:10.5665/sleep.4716
  2. Sleep Deprivation Described as a Serious Public Health Problem | American Association for the Advancement of Science. Accessed March 6, 2022. https://www.aaas.org/news/sleep-deprivation-described-serious-public-health-problem
  3. Alhola P, Polo-Kantola P. Sleep deprivation: Impact on cognitive performance. Neuropsychiatr Dis Treat. 2007;3(5):553-567.
  4. Patel AK, Reddy V, Araujo JF. Physiology, Sleep Stages. In: StatPearls. StatPearls Publishing; 2022. Accessed March 6, 2022. http://www.ncbi.nlm.nih.gov/books/NBK526132/
  5. Medic G, Wille M, Hemels ME. Short- and long-term health consequences of sleep disruption. Nat Sci Sleep. 2017;9:151-161. doi:10.2147/NSS.S134864
  6. Chung N, Bin YS, Cistulli PA, Chow CM. Does the Proximity of Meals to Bedtime Influence the Sleep of Young Adults? A Cross-Sectional Survey of University Students. Int J Environ Res Public Health. 2020;17(8):E2677. doi:10.3390/ijerph17082677
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