By: L Firstenberg

What is the Sleep Cycle

Sleep happens in a cycle, but the cycle doesn’t just go as smoothly as lay down, fall asleep, and wake up. You may go through many cycles in one night. There are two kinds of sleep cycles. Rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. REM has 4 stages and NREM has 3. They are categorized by studying the brain activity during sleep.  The cycle moves so that you can get the most out of your sleep and recharge your body. 

NREM Sleep Cycles

Stage one, the body is relaxing itself and you are drifting into a slumber. It is quite easy for someone to be woken up in this stage because they are still conscious. At this point you are still tossing and turning and your mind is wandering. Stage two, lasting only ten to twenty-five minutes, this stage has a slower breathing rate, heart rate, and the body temperature drops. It is classified as short bursts of brain activity that help you resist being woken up. Stage three is deep sleep, again body temperature, heart rate, and breathing rate drop, and the muscles are completely relaxed. This is what is critical to restorative sleep. It commonly lasts twenty to forty minutes and, as you continue to sleep, the stages get shorter. A lot more time is spent in the REM cycle.

REM Sleep Cycles

During REM sleep, we see a huge pick-up of brain activity nearing what happens in the brain when you are awake. The body experiences atonia which happens when the only muscles moving are the eyes and breathing muscles. During REM sleep, the eyes can be spotted moving quickly, even though they are closed, which is where REM sleep coins its name from. 

This high level of brain activity causes a lot of creativity in the brain and that can only lead to one amazing miracle of sleep, which is your dreams. Although dreams can occur in other stages they are most vivid and colorful in the REM cycle. Dreams are composed of subconscious thoughts, desires, and anxieties. They can even have crazy meanings. For example a dream about your teeth falling out may be about growing pains and being scared of growing up. 

Not getting enough REM sleep may cause consequences on your physical and emotional health. People with sleep apnea who are awoken many times through the night do not properly get through an entire cycle. While people with insomnia may not accumulate enough sleep to get through one stage. The sleep cycles are also extremely variable and can be affected by age, consistency in sleep schedule, alcohol, drugs, and sleep disorders. To improve your sleep cycles, you can improve your sleep hygiene. Make sure the area you sleep in is calming low light, nice pillow, calming music, and a sufficient amount of natural daylight before you sleep. 

Image source:

Could Getting More Sleep Actually Make You More Forgetful? 15 June 2016. World Economic Forum, http://www.weforum.org/agenda/2016/06/ could-getting-more-sleep-actually-make-you-more-forgetful/ Accessed 11 Nov. 2022.