Epidemiological Overview of sleep Disorders in the General Population

There are several hundred of epidemiological studies assessing different sleep complaints and disorders in the general population. This article summarizes the main findings of these studies and underlines some of the aspects that still need to be investigated. Insomnia complaint is one of the most studied sleep disturbances. Nearly one third of the general population complains of insomnia but a diagnosis is warranted in only 6% to 15% of the population. Excessive sleepiness is also another frequent complaint. However, its definition and method of assessment are so diverse that it is difficult to have a clear estimate of its prevalence in the general population: prevalence rates are ranging between 4% and 26%. Narcolepsy is a rare disorder with a prevalence averaging 0.04% in the general population. Obstructive Sleep Apnea Syndrome, often associated with insomnia or excessive sleepiness, is found in approximately 2% to 4% of the general population and has a higher prevalence in men than in women. Restless legs syndrome (RLS), depending on how it was assessed, varies from a low 1% in Asian countries to a high 19% in Northern European countries. RLS is higher in women and increases with age. Unfortunately, despite the high prevalence, sleep disorders remain poorly identified; less than 20% of individuals with insomnia are correctly diagnosed and treated. The figures are even lower for excessive sleepiness and RLS with less than 10% correctly diagnosed and treated.