Sleep disorders

In this section, the main sleep disorders will be presented with a brief description of each disorder and its characteristics.

Insomnia
Insomnia is a sleep disorder characterized by a set of symptoms related to a decrease in sleep duration that occurs more than 3 nights per week and whose causes can be psychological or physiological. Sleep onset insomnia is characterized by difficulty falling asleep and therefore a very long latency to sleep onset. Sleep maintenance insomnia refers to difficulty maintaining sleep and is characterized by numerous and/or prolonged awakenings during the night. Awakening very early in the morning is a third type of insomnia. A combination of different types of insomnia may be found in the same patient. Thus, the most common complaint among insomniacs is a short, light or non-restorative sleep. This disorder has harmful consequences for the individual as daytime fatigue and sleepiness, mood changes and irritability, impaired attention and concentration and decreased psychomotor performance.

Hypersomnia
Hypersomnia refers to all the sleep disorders that are characterized by excessive sleepiness and / or sleep attacks during the day despite a perceived normal sleep during the night. This disorder usually appears during adolescence or in the early twenties. Patients who suffer from hypersomnia have sleep attacks during the day, have naps that are involuntarily extended (sometimes over an hour) that are generally not restorative. These patients experience sleep drunkenness, are difficult to wake up and awakening is associated with confusion. We distinguish idiopathic hypersomnia (with no known cause) from secondary hypersomnia which is associated with a physiological problem such as restless legs syndrome or sleep apnea syndrome.

Narcolepsy
Narcolepsy is a disorder characterized by sudden onsets of sleep during the day. Frequently, patients also experience cataplexy and in some cases sleep paralysis and hypnagogic hallucinations. Cataplexy is defined by a loss of muscle tone without altered consciousness and is triggered by strong emotions such as anger, joy, laughter, or fear. Narcolepsy is distinguished from idiopathic hypersomnia by the periodicity of drowsiness (every two hours), the restorative quality of naps, the short duration of naps and by sleep onset REM periods.

REM sleep behavior disorder (RBD)
RBD is a parasomnia of REM sleep that occurs mainly after the age of 50 and is clinically characterized by complex and often violent motor activity (kicks, punches, escape behavior) acting out the dreams of REM sleep. In these patients, there is a loss of muscle atonia, which is normally present during REM sleep. These behaviors can result in injury to the patient himself or his bed partner. RBD may be idiopathic or secondary to neurological damage like cerebral-vascular accident or a tumor. Several longitudinal studies, including those of Drs. Montplaisir, Gagnon and Postuma have demonstrated that approximately half of patients with idiopathic RBD will develop Parkinson's disease or another dementia such as dementia with Lewy bodies within 10 years after diagnosis of RBD.

Somnambulism
Sleepwalking is a parasomnia of slow-wave sleep characterized by a series of complex motor behaviors that can range from sitting up in bed to walking around or even leaving the house. Waking up during the episode is difficult and associated with confusion. Sleepwalking is more common in children and adolescents and usually occurs in the first third of the night; it is associated with an abrupt change between the slow-wave sleep and wakefulness.

Sleep apnea syndrome
Sleep apnea syndrome is characterized by frequent pauses in breathing during sleep for more than10 seconds resulting in decreased oxygen in the blood during the night. This condition leads to short but frequent awakenings during the night which results in a decreased sleep quality. This in turn leads to daytime sleepiness, headaches and a dry mouth upon awakening, and changes in mood and irritability. Patients suffering from this problem eventually develop cognitive deficits: impairment of general intellectual functioning, attention, alertness, memory, executive functions and manual dexterity. They are also at risk of developing cardiovascular problems.

Restless legs syndrome
Restless legs syndrome is a disorder characterized by an irresistible urge to move the legs, and sometimes the arms, associated with paresthesias, motor restlessness, increased symptoms at rest with relief by activity and an increase in symptoms in the evening or during the night. This disorder leads to difficulties in falling asleep and frequent awakenings during the night.

Periodic leg movements in sleep (PLMS)
This condition is characterized by the repeated and rhythmic appearance (every 20 to 40 seconds) of leg movements of short duration. The most frequent sleep complaints in patients with PLMS are non-restorative sleep and daytime sleepiness because periodic movements cause sleep fragmentation resulting in a reduction of sleep depth and quality.

Circadian rhythm sleep disorders
This category of disorders includes all the adjustment to ambient light-dark cycle problems that can either be caused by environmental constraints (irregular schedules, job rotation, jet lag) or be of intrinsic origin (dysfunction of the biological clock, blindness, specific neurological condition). This class of disorders implies a modification of the sleep phase or of sleep-wake cycling and causes such disorders as the advanced sleep phase syndrome, delayed sleep phase syndrome, irregular sleep-wake pattern, non-24-hour sleep-wake disorder or sleep disorders in night workers.