We all enjoy a good night's sleep, but why is sleep so important and how can we ensure we are getting enough shut-eye each night? Read on to find out.

What Exactly is Sleep?

Physiologically speaking, sleep is the daily restful state all humans need to assume on a daily basis in order to replenish and live another day. It is a reduced state of motor activity in which consciousness of the surrounding world is suspended due to the diminished sensory stimulation response that occurs when a person lies down and closes their eyes.

Science has now revealed that sleep is fact a dynamic process in which the brain continues to work while we sleep. 

Some of these activities include:

• The production and release of certain proteins essential to growth (especially in children) and tissue repair.
  
  
• Replenishment to areas of the brain responsible for emotional and social functioning throughout the day.
  
  
• Helping the mind learn complicated tasks by retrieving knowledge potentially forgotten throughout the day.
  
  
• The preservation of emotional memories, whose components become unbound throughout the sleep process.

Brain Activity in Sleep   

Brain activity plays an important role in the sleep cycle. It directs the chemicals responsible for nerve signaling (neurotransmitters) to act on nerve cells in different areas of the brain whether the person is asleep or not. These nerve cells (brain cells otherwise known as neurons) control sleep by inhibiting the other parts of the brain that keep an individual awake.

5 Good Reasons to Get Enough Sleep

1. Memory and learning – the sleep cycle helps the brain in committing new information to memory via the process of memory consolidation. Scientific studies have also linked higher test results to students that had slept after learning the particular task being tested.
   
   
2. Weight and metabolism – a disturbed sleep cycle and chronic states of insomnia have been linked to a disturbance in metabolism and consequent weight gain. This can be attributed to its affect on appetite-controlling hormones and the ways in which carbohydrate is stored and processed.
   
   
3. Safety – daytime errors and mishaps such as falls, medical errors, air traffic mishaps and road accidents can statistically be linked to disturbed sleeping patterns prior to the event taking place.
   
   
4. Mood – a disturbed sleep cycle can cause an imbalanced amount of hormones and neurotransmitters, causing irritability, impatience, moodiness and concentration difficulty.Cardiovascular Health – Science has linked disrupted sleep and sleep disorders to conditions harmful to cardiovascular health, including irregular heartbeats and hypertension.
   
   
5. Disease – A lack of sleep directly affects the activity of the body’s killer cells and therefore depletes the body’s immune system. Recent studies have also shown good quality sleep patterns may play a part in the fight against cancer.
   

The 5 Stages of the Sleep Cycle    

Whilst there are five separate stages of sleep, they don’t necessarily progress sequentially. The normal sequencing is as follows:

• Stage 1
• Stage 2
• Stage 3
• Stage 4
• Stage 3
• Stage 2
  

We each go through these sleep cycle stages approxametly four or five times a night.

Stage 1

This is the beginning of the sleep cycle where wakefulness transitions slowly into a light sleep. The brain here produces the slow, high-amplitude theta waves for a brief period of approximately five to ten minutes. Some individuals report not really being asleep when woken from this stage.

Stage 2

The second stage of sleep lasts for approximately twenty minutes, commencing with a procession of ‘sleep spindles’:  are bursts of fast and rhythmic brain activity. It is in this stage the heart rate starts to slow and the body’s temperature begins to decrease.

Stage 3

The third stage of sleep is the transitional stage between light and deep sleep, and introduces the slow and deep delta brain waves.

Stage 4

The slow delta waves of Stage 4 sleep contribute to its other name, ‘delta sleep’. Bed-wetting and sleep-walking often occur when asleep during this stage, which lasts around thirty minutes.

Stage 5

Otherwise known as REM (Rapid Eye Movement) sleep, the fifth stage of sleep is the stage in which most dreaming occurs. The brain becomes increasingly active, the more active muscles relax, voluntary muscles become paralysed and the rate of respiration and eye movement dramatically increases.

Circadian Rhythms      

Circadian rhythms are the biological, twenty four hour cycle that influences when we sleep, how much we sleep and how well we sleep. They are our ‘internal clock’ that dictates many of our daily bodily functions, often influenced by:

• The state of light/darkness
• The Hypothalamus, which controls the wakefulness/sleep rhythm.
• External stimuli such as the timing of meals, alarm beeps, time zone crossing (which leads to jet lag) and night-time shift work.
  

Those who experience disturbances in the circadian rhythm often experience symptoms such as:

• Drowsiness
• Inability to concentrate
• Disturbances in appetite
• Increased risk of heart problems
• Gastro-intestinal issues
• Mental and emotional health problems
   

How Much Sleep is Enough?

• Adults need 7-8 hours per night (although some adults may function better with 5-10 hours of sleep a night)
• Teenagers need 9 hours per night
• Infants need 16 hours throughout the course of the day and night.
• Pregnant women need increased amounts of sleep, particularly in the first trimester of pregnancy.