Inclusion Criteria:
* Subjects aged 7 to 12
* Able to receive clear, age-appropriate information and to participate fully in the study
* Whose legal representative(s) are able to understand the objectives and risks of the research and to give their dated and signed informed consent.
* Subjects benefiting from a social health insurance plan (beneficiary of the legal representative(s))
* With a diagnosis made prior to inclusion of Autism Spectrum Disorder (ASD) or Attention Deficit Disorder with or without Hyperactivity (ADHD) as defined by Diagnostic and Statistical Manual 5 (DSM-5).
* With abbreviated intelligence quotient \> 80 measured by Wechsler Intelligence Scale for Children version IV (WISC-IV )no more than 6 months prior to research inclusion
* No diagnosis of: fragile X syndrome, Rett syndrome, trisomy 21, tuberous sclerosis of Bourneville, von Recklinghausen disease, Cytomegalovirus encephalitis (CMV encephalitis), congenital rubella, phenylketonuria
* No clinically significant abnormality which, in the investigator's opinion, could interfere with the implementation of the study.
Exclusion Criteria:
\- Current or past neurological problem(s) (e.g. stroke, epilepsy, meningitis, head trauma with loss of consciousness of more than 15 min, concussion, brain tumor, ...).
tumor, ...)
* Transmeridian travel (\> 2 time zones) in the month prior to study inclusion
* Presence of a mood disorder (bipolar disorder or depression) according to DSM-5 criteria
* Social jet-lag \> 2 hours (mid-point of sleep differential during weekends vs. weekdays)
* Modification of psychotropic medication in the 2 months prior to inclusion
* Use of melatonin-based dietary supplement(s)/medication(s) in the 24 hours prior to study inclusion
* Use of psychostimulant(s) within 48 hours of study entry
* Extreme chronotype (Morningness/Eveningness questionnaire score \< 10 or \> 42)
* Cognitive-behavioral therapies (CBT) targeting sleep disorders
* Participation in research involving an experimental drug which may interfere with the protocol\*.
* Minor under guardianship
* Subject in a period of exclusion (determined by a previous or current study)
* Subject in emergency situation
