They are sleep cycle dysfunctions (see box). They can be divided into three groups.
- Dyssomnia: disturbances that affect the quality or length of sleep. They are insomnia of psychological origin (inability to sleep at night), altitude, linked to the indigestion of substances (alcohol …), narcolepsy (sudden sleep that can occur at any time of day) …
- Parasomnia: abnormal behaviour during sleep but without significant disturbance or alteration in alertness during the day. They include night terrors, sleepwalking, nocturnal bruxism, sleep apnea (involuntary cessation of breathing, “apneas”, during sleep) .
- Sleep disorders of psychiatric, neurological origin or linked to other illnesses (such as depression, for example).
In France, insomnia is the most common sleep disorder. It affects about 30% of the adult population.
Sleep cycles :
Sleep is made up of a succession of cycles beginning with slow wave sleep and ending with REM sleep.
- Slow wave sleep consists of four stages:
- stages 1 and 2 correspond to light sleep: during stage 1, it is possible to be woken up by the slightest noise and one has the impression that one is not sleeping; during stage 2, the activity of the brain gradually decreases, the muscles relax, the heart slows down,
- Stages 3 and 4 correspond to deep sleep, during which the brain is no longer sensitive to external stimuli. It is during this phase that the organs replenish their energy reserves.
- REM sleep then comes with a brain activity that becomes intense again, with jerky eye movements. It is during this phase that the majority of dreams occur.
The distribution varies during the night: the beginning of the night contains more deep sleep and in the second part of the night, light and REM sleep are more important.
How can this be explained?
There are many causes of insomnia. They can be linked to a fragile psychological state (anxiety, stress, depression) or to the abuse of various substances (alcohol, coffee, medication…). A healthy lifestyle, working staggered hours or overwork can also be explanatory factors. In addition, many pathologies can cause episodes of insomnia (asthma, hyperthyroidism, allergies…).
What are the symptoms?
Insomnia results in difficulty falling asleep, multiple awakenings during the night and waking up too early in the morning. It is said to be chronic or severe when it occurs more than three times a week for more than three months. Anxious person generally cannot get sufficient sleep at bedtime because he or she is reliving the day and his or her preoccupations. Stressed individuals feel as though they are drowsy from 4 or 5 a.m. onwards. Finally, a depressed person is often the victim of early awakenings in the middle and end of the night.
A quiz to learn more about your sleep
What should I do if I have trouble sleeping?
Insomnia is a signal from the body that must alert. We must find the cause and consult a doctor to treat it. If you have trouble sleeping, it is useless to stay awake in bed for more than 20 minutes. It is better to get up and do something else. Likewise, it is advisable to get up for good in the morning as soon as you are awake. Finally, during the day, the nap should not exceed about twenty minutes.
How to avoid it?
To regain a restful sleep, it is advisable to follow a few simple rules before going to bed:
- avoid all stimulants (coca-cola, coffee, tea, vitamin C),
- don’t make a big dinner and ban the alcohol,
- Avoid playing sports after 7:00 p.m,
- favour relaxing activities (music, reading),
- go to bed at the first signs of fatigue (yawning, stinging eyes…),
- sleep in a ventilated room where the temperature is between 18 and 20 °C.