What Happens When You Sleep?

Have you ever wondered what happens when you sleep? Most of us drift into interesting and sometimes fantastical dreams that get forgotten by morning. But there’s more to sleep than you may realize. From entering REM sleep, to how our body rests and recovers by sleeping, there is so much that happens when we sleep at night or any time of day. It is more important than ever in the age of technology, smartphones, and blue-light that we understand how our sleep actually works. Let’s take a look at the different stages of sleep and how they affect your body. 

What is the sleep cycle?

The sleep cycle is the group name for the different phases of sleep that your body and mind go through during the night. The entire cycle takes one and a half to two hours to complete and on average, the cycle is completed five times a night during a seven to eight hour period. In total there are four stages of sleep. The first three are part of the Non-REM (NREM) stage. The last is the Rapid Eye Movement (REM) stage.*

Let’s break down each of these stages to understand sleep. 

Stage 1

What is it?

The first stage of sleep in the sleep cycle is the lightest. On average, it lasts between one and seven minutes and is the shortest stage of sleep. The National Institute of Neurological Disorders characterizes this stage as a shift from wakefulness to sleep. Since this is the lightest stage of sleep, waking up is fairly easy, though responses may vary. The closer one is to the next stage of sleep, the more drowsiness they may experience.*

How does the body respond? 

Depending on your stage of sleep, your physical body may respond in different ways. During Stage 1, your eyes move slowly, muscles relax, and you tend to drift in and out of sleep. Your brain is producing alpha and theta waves.*

Stage 2

What is it?

Stage two is the sleep cycle stage in which your body gets ready for a deeper state of sleep. It is still considered a lighter stage, but everything is starting to slow down at this point in the cycle. This stage lasts anywhere from 10 to 25 minutes. This stage isn’t as easy to wake up from, but the chance of being super groggy when you get up is lower than in earlier stages.* 

How does the body respond?

Everything slows down, heartbeat, breathing, and eye movement. The muscles become relaxed and your body’s internal temperature drops. Scientists have discovered that this stage is characterized by short bursts of electrical energy in the brain called sleep spindles. Sleep spindles are suggested to be an important part of memory consolidation.* 

Stage 3

What is it?

Where the first and second stages were preparation for sleep, the third stage is for deep sleep. Lasting 20 to 40 minutes, this stage is marked by the brain’s development of Delta waves. Delta waves are the slowest brain waves. Waking from this stage is extremely difficult. Once entered, sleepers may not notice bright lights or loud sounds. If you do wake during this stage, you may be incredibly disoriented.* 

How does the body respond?

We’ve mentioned in previous articles that during sleep, the body works to repair itself. The third stage is where this healing takes place. Muscle, bone, and tissues are repaired and made stronger, along with boosting the immune system. This is also arguably the most important stage of the sleep cycle for those who exercise and whose muscles need to repair and regenerate.*

What is Rapid Eye Movement (REM)?

What is it?

REM is by far the most interesting stage of sleep. While this is the deepest stage of sleep, this is also when the mind and body are the most active. The entire stage lasts from 20 to 40 minutes, getting longer as the night progresses. Though it isn’t completely understood, scientists believe this stage is critical to memory storage and learning.*

REM is also the point in the sleep cycle when the most vivid dreams occur. Though you may only remember one dream (or none at all), it’s understood that we have several dreams throughout the night. The reason for dreaming is unknown but dreams themselves have been split into four different categories: Normal, anxiety, nightmare, and “false awakenings”, or waking up in the dream when you’re actually still sleeping.*

How does the body respond to REM Sleep?

REM is the most active stage of sleep and is called ‘REM’ because the eyes shift from side-to-side rapidly. Along with the eyes, breathing, heart rate, and blood pressure increase, while the muscles become paralyzed. Since this is the time for the most vivid dreams, the paralysis is the body’s way of preventing you from acting out your dreams.* 

How can you ensure you get the best sleep?

Great question! There are a few things you can do to better your chance of having a blissful and invigorating sleep. 

First, use your sleep cycle to your advantage. If you know you need to wake up at a certain time, you can use an online sleep calculator to help you figure out when you should fall asleep to ensure you wake up between sleep cycles. Waking between cycles gives you the ability to be refreshed and not groggy. 

Second, make your environment sleep-friendly. When it’s time for bed, dim the lights, turn the temperature down, and put away your electronics.

Lastly, invest in a bedding set that’s going to keep you comfortable. We highly recommend switching to bamboo viscose bedding. It is breathable and temperature regulating, making it cooler than traditional cotton sheets while maintaining strength and softness. It’s even hypoallergenic, warding off common household non-living allergens! Check out the Cosy House Bed Sheets here!

Resources:

What is REM sleep? National Sleep Foundation. (2020, November 1). Retrieved from https://www.thensf.org/what-is-rem-sleep/.

Van Dongen, H. P., Maislin, G., Mullington, J. M., & Dinges, D. F. (2003). The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep, 26(2), 117–126. https://doi.org/10.1093/sleep/26.2.117.

Chapter 30: Sleep. (2021, July 6). Grossmont College. https://socialsci.libretexts.org/@go/page/12428.

Dimitriu, A. (2018, July 26). Am I sleep-deprived and tired – or depressed? PRWeb. Retrieved from https://www.prweb.com/releases/am_i_sleep_deprived_and_tired_or_depressed/prweb15642255.htm.