Abstract
Sleep-related disorders, especially in teenagers, have been receiving increasing attention. Here, we describe the
current situation regarding sleep disorders and the habituation of sleep in teenagers, as well as the relationship
between neurodevelopmental and sleep disorders. In teenagers, habituation of sleep, which includes eveningness, eveningness-related sleep insufficiency, and daytime sleepiness, has been reported to be associated with
the increased prevalence of the two-income family, the influence of parents’ lifestyles, and excessive screen time
on computers and mobile devices. The rapidly rising Internet utilization rate is related to increased screen time,
which promotes delayed bedtimes, especially among primary schoolchildren. It has been reported that the more
frequently Japanese low-teens go to sleep at a delayed bedtime, the more readily mental health disorders can
develop. According to the International Classification of Sleep Disorders-Third Edition, sleep disorders in young
adults contribute to restless legs syndrome, hypersomnia, and circadian rhythm sleep–wake disorders. It is difficult
to diagnose restless legs syndrome in small children because their communication is limited. Hypersomnia has
been shown to contribute to narcolepsy and idiopathic hypersomnia. Generally, idiopathic hypersomnia involves
less frequent sleep-onset rapid eye movement (REM) periods than narcolepsy, as estimated by polysomnography
and multiple sleep latency tests. Although narcolepsy includes REM-related symptoms such as catalepsy and
sleep paralysis, idiopathic hypersomnia is diagnosed without REM-related symptoms. Delayed sleep–wake phase
disorder, which is considered a circadian rhythm sleep–wake disorder, is often found in teenagers and can easily
lead to diminished social life activity because it causes extreme difficulty awakening in the morning. In terms of
neurodevelopmental disorders, sleep disorders such as restless legs syndrome, nocturnal enuresis, and sleep apnea
syndrome are often said to complicate children with attention-deficit/hyperactivity disorder. Therefore, general
practitioners and hospital doctors should refer teenagers likely to be experiencing hypersomnia or neurodevelopmental disorders to specialized institutions because most of these cases require early medical intervention.
