Sleepiness in patients with obstructive sleep apnoea - daytime course and impact of nocturnal respiratory events.

BACKGROUND Obstructive sleep apnoea (OSA) is a condition leading to excessive daytime sleepiness. The aim of the study was a) to study course of daytime sleepiness in patients with OSA and b) to find the most important nocturnal polysomnography parameters influencing daytime sleepiness in OSA. METHODS The cohort consisted of forty-five patients (6 women, 39 men) diagnosed with OSA. All patients underwent polysomnography, Multiple Sleep Latency Test (MSLT) and rated subjectively their daytime tendency to sleep with the Epworth Sleepiness Scale. RESULTS Sleep latency was significantly longer at 15:00 and at 17:00 hours compared to previous tests. A significant negative correlation was found between the mean of the MSLT sleep latency and a number of awakenings, the apnoea/hypopnoea index and oxygen desaturation index values. CONCLUSIONS The study showed the sleep latency prolongation at 15:00 and 17:00 hours respectively and confirmed connection of excessive daytime sleepiness to fragmentation of nocturnal sleep and OSA severity.