The sleepy patient

Sleepiness is a common symptom affecting perhaps 10% of the adult population. It is defined as sleep episodes occurring at an inappropriate time or under inappropriate circumstances, such as when reading or driving. Sleepiness is commonly measured using the Epworth sleepiness scale. Physiologic measures are also used to estimate sleepiness and include the Multiple Sleep Latency Test. Sleep deprivation or inadequate opportunity to sleep leads quickly to clinically significant excessive sleepiness. Alternatively the sleepy patient may be experiencing interrupted sleep caused by sleep-disordered breathing (i.e. obstructive sleep apnoea), periodic limb movements of sleep, or disease (e.g. arthritis or obstructive lung disease). Rarely, narcolepsy or primary hypersomnia is the cause. Diagnostic investigations, including overnight oximetry and polysomnography, are discussed.