The body goes through different stages of sleep each night, each with unique restorative functions. Sleep without these stages may lead to deprivation of vital elements that help you live a quality life. This article highlights how sleep cycles work in an effort to better understand the role of sleep.

Sleep cycle, what is it?

There are 5 stages of sleep each lasting an average of 90 minutes. They are subdivided into two:

  1. Rapid eye movement sleep
  2. NREM sleep is dreamless sleep.

Non-Rapid Eye Movement stage

During the non-rapid eye movement sleep stage:

  • The brain waves on the electroencephalographic recording are usually slow and of high voltage.
  • There is slow and regular breathing
  • Blood pressure is low

There are 3 stages of non-rapid eye movement sleep. The stages last for 5 to 15 minutes.

Stage 1

This stage lasts for 5 to 10 minutes. The eyes are closed but they can easily be awakened. One may not perceive that they are asleep during this stage.

Stage 2

In this stage, the heart beat slows and the body temperature drops. One is in light sleep and the body is ready to get into deep sleep. This accounts for 40% to 50% of sleep time.

Stage 3

This is deep sleep stage. It is also called delta sleep or slow wave sleep. It is hard to be aroused and if awakened, one feels disoriented for a few minutes.

It is during this stage where tissues grow, bone and muscle builds and the immune system is strengthened. It accounts for 20% of sleep in adults.

Rapid eye movement

Rapid eye movement stage of sleep happens 90 minutes after one has slept. There are rapid bursts of rapid eye movements. Most dreaming occurs in this phase of sleep, reason as to why there is rapid eye movement. The visual images presented during sleep are the cause of eye movements.

It is characterized by:

  • Irregular heart beat
  • Irregular breathing

Even as the eyes dart back and forth, up and down, the muscles that move the body are paralyzed. Other muscles though, like the heart muscles and diaphragm continue functioning as usual.Rapid eye movement stage is important in sleep as it makes up approximately less than 25% of total sleep time. REM sleep is important for the brain as it helps preserve memory and maintain the required neurological connections.

  • REM sleep is paradoxical sleep because it is similar to wakefulness. Although the body is paralyzed, the brain keeps firing and sending signals to nerves supplying the eyes.

Do sleep cycles change with age?

Changes in sleep cycles occur with aging. Stage 3 of non rapid eye movement sleep declines as one ages, while stage 1 of NREM increases with age.

  • Older people spend less time in the more restorative stages of sleep and more time in lighter sleep.
  • Babies usually spend up to 50% of their sleep in the REM stage while adults spend 20%.


A lot happens in your body when asleep; the brain is active as it keeps sending different signals to various parts of the body. It is therefore essential for you to take foods that are rich in melatonin and other sleep inducing foods for a better good night sleep.