Chronic insomnia is often presented with many medical and psychiatric disorders, and its underlying aetiology needs to be identified by using Polysomnography (PSG) to achieve safe and effective management. Obstructive Sleep Apnoea (OSA) and Parasomnia such as Limb Movement Disorder (PLMD) are common primary sleep disorders that can lead to chronic insomnia. Patients with chronic insomnia need to be evaluated and managed.

Methods: Across sectional epidemiological study for a total number of 397 patients diagnosed with long history of chronic insomnia with mental disorders using PSG reports as marker, seen at Sleep Disorder Unit in Kuwait Centre for Mental Health (KCMH).

Results: By reviewing PSG montage and reports of 397 individuals, 38.5% of chronic insomnia related to mental illness, 3.5% only related to primary insomnia, 22.1% had Obstructive sleep apnoea, 5.5% had hypersomnia, 5.2% had narcolepsy, 2.77% PLMD, 1.25% had Circadian Rhythm Disorder (CRD) and 5.79% of sample were not done by patients

Conclusion: Using PSG as a marker for chronic insomnia in individual with mental illness and evaluates the underline cause of chronic insomnia. It is cost effect on the long term and an adequate strategy to treat insomnia among our patients.

Keywords: Insomnia, obstructive sleep apnoea, mental disorders, polysomnography, kuwait centre for mental iliness