1. Overview and definition

 Circadian rhythm sleep–wake disorders are classified in the International Classification of Sleep Disorders, Third Edition (ICSD-3). The most common type, delayed sleep–wake phase disorder (DSWPD), is also recognized in ICD-11 and DSM-5.

 CRSWD occurs when an individual’s internal biological clock fails to synchronize properly with the Earth’s natural 24-h light–dark cycle. This makes it difficult to sleep and wake at socially appropriate or desired times.

Common types are as follows:

• DSWPD: late bedtimes and wake times.
• Advanced sleep–wake phase disorder (ASWPD): very early bedtimes and wake times.
• Irregular sleep–wake rhythm disorder (ISWRD): no clear sleep pattern.
• Non–24-h sleep–wake rhythm disorder (non-24): sleep times that shift later each day.

In children and adolescents, these disorders often contribute to school attendance problems and can worsen existing difficulties.

2. Symptoms

 DSWPD is the most common type, characterized by consistently late bedtimes and wake times. Even when children want to sleep earlier, they find it difficult to fall asleep and consequently cannot wake up at the desired time. Symptoms often emerge after long school holidays. Forcing early waking times despite a delayed natural rhythm can create additional stress, leading to a vicious cycle.

 ASWPD involves very early sleep onset and awakening. Children feel sleepy in the early evening, go to bed early, and wake up much earlier than desired. Some may lie awake for hours and then fall back asleep (“second sleep”), which can disrupt their intended schedule. This condition is sometimes mistaken for excessive sleepiness or difficulty waking up.

 ISWRD lacks a clear sleep–wake pattern, with sleep occurring irregularly throughout the day. This is more common in children with neurodevelopmental conditions or genetic disorders, requiring frequent daytime naps alongside fragmented nighttime sleep.

 Non-24 involves sleep–wake times that gradually shift by 30 min to 1 h each day. Although the human circadian clock naturally runs slightly >24 h, this disorder occurs when normal adjustment mechanisms, primarily exposure to morning sunlight, fail to work properly. In children and adolescents, this often appears in the early stages of school avoidance, when exposure to natural light and social cues becomes limited.

3. Diagnosis

 Minor changes in sleep–wake timing are normal. However, when individuals strongly desire to sleep and wake at appropriate times, practice good sleep habits, and still experience significant difficulties that interfere with daily life, the condition may be considered a medical disorder.

 Diagnosis in children and adolescents can be challenging because young people often have mixed feelings about sleep. They may say they want to go to bed and get up on time while feeling, “I don’t want to sleep yet” or “I don’t mind not being able to wake up.” Within social expectations, children may genuinely believe, “I really want to wake up but somehow can’t.”

 Medical evaluation considers these complexities and may include detailed interviews and sleep diary entries to understand the child’s actual sleep–wake patterns and underlying challenges.

4. Treatment and management

Education and sleep hygiene: Correcting inappropriate sleep practices is essential. Education should include both the child and parents or caregivers. Many parents recognize that excessive screen time before bedtime negatively affects sleep and hope that healthcare providers will reinforce this message. However, parents may overlook how evening activities, such as cram schools or sports, can disrupt sleep.

Balanced approach: Even when some sleep habits are not ideal, if the child maintains reasonable sleep–wake timing and enjoys a fulfilling social life, strict intervention may not be necessary. However, when families seek medical care because of significant struggles, behaviors that seem “admirable” and those that are truly “healthy for the body” must be distinguished.

Addressing underlying factors: When children understand what they should do but cannot act on this knowledge, underlying issues should be considered. These may include emotional difficulties from experiences, problems with time perception, or developmental and cognitive differences.

Collaborative care: Encouraging children to keep sleep diaries and actively participate with healthcare providers supports progress and provides valuable insights. Once individual challenges are clearly identified and realistic physical, psychological, and social goals are established, treatments such as light therapy or melatonin-related medications can be effectively introduced.

GO, Soken
Department of Pediatrics, Juntendo University Urayasu Hospital