Disturbed sleep is very common in almost all neuropsychiatric and neurodevelopmental conditions (NDPCs), such as autism, attention deficit and hyperactivity disorder, schizophrenia, and bipolar disorder. While it is understandable that the symptoms of such conditions would lead to sleep disruption and also that sleep disruption would worsen symptoms in these conditions, Irish researchers have now found new genetic associations between some of these conditions and chronotype, the behavioral manifestations of an individual's circadian rhythm ("night owl" or "early bird)".