General Health

Sleep Revolution 2: The Science of Sleep

There had been much debate on the subject of sleep. The current trend is giving less attention to sleep. Blue lights from digital screens were created to fight sleep and keep more users glued to their smartphones, LEDs and PCs. Unfortunately, many of us are unaware of the impact of this lifestyle changes. It’s a SLEEP-MORE REVOLUTION.

Let the Revolution Begin!!!

What is Sleep?

Before now, very little was known about the science of sleep, because researchers decided to sleep on the subject of sleep. Research around the subject of sleep has become fascinating in recent times and so much shocking discoveries have been made.

Sleep is a reversible behavioural state of perceptual disengagement from and unresponsiveness to the environment (Carskadon & Dement in Principles and Practice of Sleep Medicine 2005; p.13).

Sleep is complex and many times it is seen as an intermediate state between wakefulness and death.

Sleep is regulated by nerve signalling chemicals called neurotransmitters that act on the different group of nerve cells or neurons in the brain. Research suggests that a chemical called adenosine builds up in our blood while we are awake and once the adenosine reaches a certain level, it causes drowsiness. This adenosine gradually breaks down while we sleep and the cycle continues.

The Circadian Clock

There is time set for everything says the Holy Book. Our body system is no exception. The circadian clock regulates sleeping patterns; we are more likely to want to sleep at night than during the daytime. The hypothalamus area of the brain sets its sleep patterns according to when it is light outside and when it is dark through the light or darkness detected by the retina. When it starts getting dark outside, the hypothalamus signals to the body to start creating sleep hormones, like melatonin, and to drop the human’s body temperature and prepare for sleep. In the morning, when light is sensed, a signal is also sent to the body to produce hormones, (cortisol), that wakes the body up. ‘

Adding artificial lights to the cycle confuses the whole clock. Research has found that exposure to blue light suppresses the production of melatonin more than any other type of light. This explains why you could stay up late at night staring at your screen effortlessly without dozing, yet you struggle to stay awake when reading a printed material.

The Stages of Sleep

Generally, sleep is classified into two categories

  • the Non-Rapid Eye Movement Sleep (NREM, 75% of the night) and
  • the Rapid Eye Movement Sleep (REM, 25% of the night)

The NREM comprises of 4 stages (Stage 1, 2, 3, & 4) and it is followed immediately by the REM sleep.  We are expected to pass through these five stages to make a complete sleep cycle. It takes about 90-110minutes to complete a Sleep cycle. Once a sleep cycle is achieved, it begins again from stage 1.

N1 (formerly Stage 1)

  • Between being awake and falling asleep
  • Also called the light sleep phase
  • We drift in and out of sleep and can be awakened easily.
  • The eye moves very slowly and muscle activities also slow down.

N2 (formerly Stage 2)

  • Onset of sleep
  • Gradual loss of consciousness
  • Breathing and heart rate are regular
  • Body temperature drops (sleeping in a cool room is helpful)

N3 (formerly Stage 3 and 4)

  • Often called deep sleep
  • Deepest and most restorative sleep
  • Blood pressure drops
  • Breathing becomes slower
  • Muscles are relaxed
  • Blood supply to muscles increases
  • Tissue growth and repair occurs
  • Energy is restored
  • Hormones are released, such as Growth hormone, essential for growth and development, including muscle development

 It is very difficult to wake someone during the N3 phase, If you mistakenly wake up during deep sleep, you often feel groggy and disoriented for several minutes. Some children experience bedwetting, night terrors, or sleepwalking during deep sleep.

REM (25% of the night):

First occurs about 90 minutes after falling asleep and recurs about every 90 minutes, getting longer later in the night

  • Provides energy to brain and body
  • Supports daytime performance
  • Brain is active

The brain in REM sleep can even be more active than when we are awake. It often appears as if we are awake. Eyes moving back and forth, heart rate increases, blood pressure rises, and males develop penile erections. It has been observed that this is where we tend to have dreams and some bizarre illogical tales. Dreams happen towards the end of REM sleep and usually precedes waking up.


Body Activities in Sleep

Body Temperature Trying to sleep in a very hot environment can be very difficult because just before we fall asleep, the body is expected to lose some heat to the environment and it is believed to help induce sleep. When we sleep, the body temperature reduces by about 1 to 2°F and falling to its lowest point during REM sleep. As a result, less energy is required to maintain body temperature. This is one of the primary functions of sleep- to conserve energy.

Respiratory Changes breathing patterns change significantly during sleep. When we are awake, breathing is usually irregular as it is affected by speech, emotions, exercise, posture, and other factors. As we go through the stages of non-REM sleep, our breathing rate slightly decreases and becomes very regular. During REM sleep, there is an overall increase in breathing rate as we prepare to wake up. 

Cardiovascular Activity One of the main functions of sleep is to give the heart a chance to rest from the constant demands required during wake hours. During non-REM sleep, there is an overall reduction in heart rate and blood pressure. During REM sleep which is the last stage before waking up, there is an overall increase in blood pressure and heart rate.

Increased Physiological Activity during Sleep Contrary to expectations, some physiological processes increase during sleep. For example, one of the greatest changes induced by sleep is an increase in the release of Growth hormone. Certain physiological activities associated with digestion, cell repair, and growth is often greatest during sleep, suggesting that cell repair and growth is an important function of sleep.

With all of these events happening in Sleep, wouldn’t you rather Sleep More?

Did you learn anything new? Let us know, leave a comment


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Dr. Lucky Aziken
Dr Lucky Aziken, a multitalented Optometrist believes health education is key towards achieving a healthy society. He is passionate about knowledge and creatively communicates his thoughts. He loves reading, writing and connecting people.

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