Stages of Sleep

In the midst of these hard times it is our good health and good sleep that are enjoyable. 

According to sleep researchers, there are two main types of sleep namely Non-REM (Non-Rapid Eye Movement) sleep and REM (Rapid Eye Movement) sleep.

Non-REM sleep consists of three stages, each deeper than the previous.

REM sleep is the one when most dreams occur. Your eyes move rapidly during this stage, that's why it is called Rapid Eye Movement sleep.

Hypnogram showing sleep cycles

Non-REM sleep

Stage N1 - This is slow transition to sleep and this stage lasts about 5 minutes. Eyes move slowly under the eyelids, muscle activity slows down, and you can be easily awakened.

Stage N2 - This is light sleep lasting from 10 to 25 minutes. Eye movement stops, heart rate slows, and body temperature decreases.

Stage N3 - This is deep sleep where extremely slow brain waves called delta waves are interspersed with smaller, faster waves. And it is very difficult to wake someone from this stage.

In deep sleep, there is no eye movement or muscular activity. Deep sleep is a time when the body repairs itself and builds up energy for the day ahead.

REM sleep

This is dream sleep where your eyes move rapidly. Breathing becomes more rapid, irregular and shallow and limb muscles are temporarily paralyzed.

Also, heart rate increases, blood pressure rises and males develop erections.

Just as deep sleep renews the body, REM sleep renews the mind. REM sleep plays a key role in learning and memory. During REM sleep, your brain consolidates and processes the information you’ve learned during the day, forms neural connections that strengthen memory, and replenishes its supply of neurotransmitters, including feel-good chemicals such as serotonin and dopamine that boost your mood during the day.

It’s not just the number of hours in bed that is important—it’s the quality of those hours of sleep. If you’re giving yourself plenty of time for sleep, but you’re still having trouble waking up in the morning or staying alert all day, you may not be spending enough time in the different stages of sleep—especially deep sleep and REM sleep.

Your internal 24-hour sleep-wake cycle, otherwise known as biological clock or circadian rhythm, is regulated by processes in the brain that respond to how long you’ve been awake and the changes between light and dark.

At night, your body responds to the loss of daylight by producing melatonin, a hormone that makes you sleepy. During the day, sunlight triggers the brain to inhibit melatonin production so you feel awake and alert.

If you can't avoid working in shifts, then you may want to be careful on how to cope up with night shifts.

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