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Exploring the stages of sleep

Written by Vindya Senanayake

Hi there! Today, let’s talk about something we all know but somehow fail to practice daily. We have all heard the phrase ‘a good 8-hour sleep is important’; but is it? In our nightly journey through slumber, we delve into the intriguing stages of sleep to uncover their secrets.

We often take sleep for granted ignoring the importance of sleep benefits like improving memory, attention, productivity and lowering risk of diseases. Over the decades, the quality and quantity of sleep people have gotten has decreased substantially. Main reason for this has been the overuse of social media especially during the night which allows the exposure of blue light to reduce the quality of sleep by disrupting the circadian rhythm. Digitalization has gotten people engaging in social activities at the expense of sleep. 

In 1929, researchers studying sleep identified that during our sleep the brain fires specific brainwaves. Later, using the technique these patterns were discovered to represent specific stages of sleep. As such, our sleep can be categorized into two main phases as REM (rapid eye movement) and non-REM sleep, and we go through multiple cycles of these phases each night. 

Sleep in different stages

During the awake period, the brain fires rapid signals and is recorded in high frequencies, this is attributed to responding to different stimuli. However, as we begin to fall asleep, this fast-paced neural activity starts slowing down and the brain starts firing low frequency high amplitude waves that gradually decrease over the first hour into sleep. This period of non-REM sleep is further broken down into 4 stages: drowsy, light sleep, moderate-deep sleep, and deep sleep. The early stages of non-REM sleep follow theta waves. These are much slower in frequency than when we are awake. As it gradually decreases, the next phase of wave patterns the brain fires is called the delta waves. These are characteristically slower with high amplitudes and represent the deepest sleep stage. During this phase, the body enters a recharge and repair period which supports tissue growth and immune strength.

Following this non-REM sleep, the brain enters REM sleep where neuronal activity is similar to that of the awake state with high frequency wave patterns. However, this is short lived for about 10 minutes and the cycle re-enters the non-REM sleep. The REM sleep phase at the end of the cycle is when the brain fires beta waves. Beta waves are important in our cognitive regulation, problem solving and memory. According to EEG results, on average we go through about 2 cycles of non-REM and 4 cycles of REM sleep each time. Interestingly, the duration of REM sleep decreases as we age from around 8 hours at birth to around 45 minutes by the age 70. Although sleep scientists have unveiled these facts about our sleep, the physiological meaning of sleep is not clearly understood.

                   Figure 28.5. EEG recordings during the first hour of sleep.

Improving the quality of sleep in different stages

Lisa Matricciani at the University of South Australia studying the effects of sleep on human health, highlights the importance of consistent sleep schedules. On average, every adult should get a good sleep of 7-8 hours every night and with practice this coincides with our body clock. However irregular sleep patterns and stimulants like coffee, stress and excitement disturbs the circadian rhythm making us feel exhausted even after a good night’s sleep. Hence, why these scientists advise on avoiding caffeine later in the day and bright light at least an hour before bedtime.

There are different ways to improve quality of sleep, and this can be customized according to the individuals’ preferences. However, a few of the recommended methods to improve sleep quality are listed here. 

  1. Avoiding any caffeinated beverages after 3pm as caffeine stimulates the brain to be active. This not only makes it harder to fall asleep at night but also reduces the duration of non-REM sleep.
  2. Individuals with light sleep conditions may be benefited by listening to soothing and relaxing sleep music through the night to ensure quality of sleep.
  3. As stress is known to be a culprit of good sleep, reducing stress involved in conflicts, school/work related deadlines and other problems could help in getting quality sleep.
  4. Being consistent with sleep schedules trains our circadian clock to maintain its rhythm making it easier to fall asleep and wake from restful sleep each day.
  5. Being physically active during the day also aids in quality of sleep.

Hence, much importance of sleep has been shown during the past and it is evident in our daily activities. The way we think, act and perform is all dependent and is affected by the quality of sleep we get. Sleep deprivation can not only make us exhausted, groggy, and oblivious; it also affects our health. People with sleep deprivation are more prone to conditions like obesity, cardiovascular diseases, early onset of diabetes and even reduced life span. Therefore, getting a good quality restful sleep is just as important to lead a healthy and happy life. 

Suggestions for a good sleep

  • Pay attention to the environment. Use room darkening shades, sleeping masks, earplugs to signal the body to enter the sleep cycle and to avoid external stimuli disturbing the sleep.
  • Eat a light dinner and have dinner 3-4 hours before going to sleep.
  • Clear the mind by writing everything that is cluttering the mind and brings worry into the sleep. 
  • Write down things to get done/ daily plan for the following day.
  • Meditate for a brief time right before falling asleep to quiet the wandering mind.


CDC. “Sleep Hygiene Tips – Sleep and Sleep Disorders.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 13 Sept. 2022,

Forrester, Nikki. “How Better Sleep Can Improve Productivity.” Nature, vol. 619, no. 7970, 17 July 2023, pp. 659–661,, Accessed 19 Aug. 2023.

Hobson, J. Allan (John Allan). Sleep. New York : Scientific American Library, 1933.

Purves, Dale, et al. “Stages of Sleep.”, Sinauer Associates, 2001,


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