ISWRD has various causes, including neurological disorders such as dementia (particularly Alzheimer's disease), brain damage, or intellectual disabilities.

[citation needed] A physician specializing in sleep medicine may ask patients about their medical history; for example: neurological problems, prescription or non-prescription medications taken, alcohol use, family history, and any other sleep problems.

[6][7] A neurological condition or another medical problem may be suspected, in which case, blood tests, a CT scan or an MRI may be used.

It charts brain waves, heart beat, muscle activity, and breathing during sleep.

[citation needed] Treatment for irregular sleep–wake rhythm tries to enable the body clock in the brain, such that a normal long sleep period at night can be achieved.

[6][7] Exposure to light during the daytime and activities occurring at regular times each day may help to restore a normal rhythm.

Affected individuals with dementia should not be prescribed sleep-promoting medications (sedatives) for ISWRD due to the increased prevalence of adverse effects in this group outweighing the possible benefits.

Other major sleep research centers are in Tel Aviv in Israel, Munich in Germany and in Japan.