These disorders are characterised by excessive daytime sleepiness not explained by disturbed nocturnal sleep or misaligned circadian rhythm. They include narcolepsy, idiopathic hypersomnia, and related presentations. The Multiple Sleep Latency Test (MSLT) and Maintenance of Wakefulness Test (MWT), performed following PSG, are gold-standard tools to quantify sleep latency and assess for pathological REM sleep onset. Precise testing protocols are essential for differential diagnosis and management.
