[Sleep in adolescents and its disorders. A survey in schools].

OBJECTIVES Numerous studies emphasized the high prevalence of sleep problems in adolescents. However, it remains to be seen whether these problems are developmental or if they are related to pathological conditions. In order to try to answer this question, we conducted an epidemiological study investigating the prevalence and correlates of sleep disorders in a population of high school adolescents. METHOD The sample for this investigation consisted of 652 high school students (344 males and 308 females), aged 13 to 19 years (mean age: 15.1 1.2 years), attending colleges in the North of France. Data for the study were obtained by means of revised versions of the INSERM self-report questionnaires for adolescents. One questionnaire included 113 response choice items investigating the sleep parameters and the sociodemographic, behavioural, health, and environmental condition of the subject. This questionnaire was completed by a self-portrait questionnaire including 27 response choice items about mood, anxiety, instability and the quality of relations with others. In addition, a clinical examination was performed by the clinicians of the school health department in order to investigate the medical history of the subject and his (her) pubertal development. RESULTS In a first step, statistical analysis showed some significant differences in sleep rates and troubles between males and females. If the total sleep time was found similar in males and females, females were found exhibiting significantly earlier bedtime (p<0.01) and waking time (p<0.005) than males. In addition, trouble falling asleep (p<0.0001), nightmares (p<0.001), need for daytime sleep (p<0.05), and stimulant pill intake (p<0.05) were found significantly more frequent in females. Then, the adolescents were classified into two subgroups. "Insomnia group" included the students who answered "often" or "always" to one of the five questions about: having trouble falling asleep, the occurrence of early awakenings, their need for daytime sleep, sleeping pill intake, and bad sleep quality. "Non insomnia group" included those who answered "never" or "sometimes" in response to the five questions. Results showed that 233 adolescents (35.7%) exhibited persistent sleep disorders, insomnia type. 40.2% of females and 31.6% of males were included in the "insomnia group" (p<0.05). Pubertal development was found significantly more advanced in the "insomnia group" adolescents, more particularly in females. In the same way, concerns about body weight (46.7% vs 38.8%; p<0.005), size and shape (15% vs 8%; p<0.01) were found significantly more frequent in the "insomnia group"; 32.3% of the "insomnia group" adolescents vs 17.9% in the "non insomnia group" reported health problems (p<0.0001). School difficulties were found significantly more frequent in the "insomnia group" compared to the "non insomnia group". The proportion of subjects who have previously repeated at least one school year (p<0.01), who reported bad school performances (p<0.01), and who reported to be "sometimes" or "often" away from school (p<0.01) was significantly higher in the "insomnia group" than in the "non insomnia group". In the same way, data showed that school investing was also significantly weaker in the "insomnia group" adolescents (p<0.01). The proportion of subjects who believed that their relations with parents (12.4% vs 6%; p<0.05), teachers (21.4% vs 10.5%; p<0.0001), or peers (10.2% vs 4.1%; p<0.002) was found significantly higher in the "insomnia group". Risk behaviours were also significantly more frequent in the "insomnia group" adolescents: suicidal ideation (25.1% vs 11.7%; p<0.001), suicide attempt (7.3% vs 3.6%; p<0.05), psychotropic drug use (11% vs 4.9%; p<0.02), regular stimulant drug use (10% vs 5.1%; p<0.005), regular tobacco use (7.8% vs 2.2%; p<0.001), regular alcohol use (13.3% vs 8.3%; p<0.05), and illicit drug use (5.2% vs 1%; p<0.001). Lastly, all the dimensions of the self-portrait were found significantly more affected or negative in the "insomnia group" than in the "non insomnia group". For example, the proportion of subjects who described themself usually sad (10.2% vs 3.4%; p<0.001), anxious (54.9% vs 40.5%; p<0.0001), downcast (41.1% vs 32.6%; p<0.05), or instable (56.9% vs 41.7%; p<0.0001) was significantly higher in the "insomnia group". CONCLUSION In this descriptive study, if some data suggest that pubertal development may be involved in the sleep rates or troubles observed in adolescents, the results also show that persistent sleep disorders are significantly associated with physical, psychological or social difficulties. In summary, this study shows that it is essential to take an interest in the quality of sleep in adolescents, which may be a way to approach their psychosocial difficulties.