Définition :

Sleep is a natural state of unconsciousness without loss of reflexes, accompanied by a progressive decrease in muscle tone. The regulation of the sleep-wake alternation is controlled by a dual process: homeostatic and circadian.

- The circadian biological clock = internal biological clock that aligns to the alternation of day and night and is expressed in the body by a drop in temperature.
- The homeostatic process = sort of timer that alternates periods of awakenings and sleep.

An adult needs an average of 8 hours of sleep per day.

Sleep cycles:

- Falling asleep: slower breathing, the muscles relax, consciousness decreases
- Light slow sleep: eye and muscle activity are reduced. It is easy to wake up at that time (50% of total sleep time).
- Deep slow sleep: time of recovery of the accumulated physical fatigue. It is difficult to wake up during this phase (20% of total sleep time).
- REM sleep: the dream stage, REM sleep is characterized by a mixture between deep sleep and awakening signs (eg increased heart activity, irregular breathing).

Signs of sleep disorders: 

- Tiredness
- Sleepiness during the day
- Irritability
- Mood disorders
- Night Awakenings
- Difficulty falling asleep

 Causes of sleep disorders: 

- Stressful events
- Poor eating habits
- Use of medication
- Respiratory sleep Disorders

Tips in case of sleep disorders:

1/ Getting out of bed for 20 to 30 minutes minimum and return to the bedroom when the signs of sleep occur
2/ Do not rush on a sleeping pill which has negative effects in the medium and long terms (amnesic effect, anxiolytic effect, dependency etc.)
3/ Do not use screen but instead read books because this activity is much more soothing
4/ Relax and focus on your breathing and relax
5/ Adopt a healthy lifestyle to prevent sleep problems: exposing yourself to sunlight, do not drink stimulants (coffee, tea, cola, ...) after 3pm, do not practice physical activity at night, do not take hot bath, do not make too long or too late nap, do not consume too rich and heavy meals, encourage relaxing activities in the hour before bedtime (herbal tea, reading, relaxation, ...), go to bed only when you feel sleepy, choose fixed times of sunrise and sunset.