Background: Excessive daytime sleepiness is a common complaint among patients with obstructive sleep apnea (OSA). On the contrary, OSA has been cited as the most common medical issue linked to excessive daytime sleepiness. In patients with OSA, there is considerable interindividual unpredictability in sleepiness, the determinants of this variability are obscure; also, there is disparity in data correlating subjective with objective sleepiness.

Aim: The aim of this research is to survey the predictors that assess sleepiness in patients newly diagnosed with and how they correlate to the degree of OSA severity.

Methods: A cross-sectional research of 80 patients with recently diagnosed OSA using polysomnography (PSG) (apnea–hypopnea index ?5/h). Subjective sleepiness was estimated by Epworth Sleep Scale (ESS) (?10). However, objective sleepiness was determined by Psychomotor Vigilance Test (PVT) (mean lapse ?2). Participants were also analyzed using the basic language Morningness scale, the STOP-BANG, and Berlin Questionnaires, and the interleukin 6 level was tested.

Results: There were four groups of participants (1: sleepy by ESS and PVT, 2: sleepy by PVT only, 3: sleepy by ESS only, and 4: non-sleepy reference group). Sleepiness was found to be protected by longer habitual sleep duration, morning chronotype, and higher sleep efficacy (P0.001 and OR=0.549 & p=0.01 and OR 0.114& p0.001 and OR=0.025, respectively). Sleepiness was attributed with no specific chronotype and a greater Arousal index (p=0.043 and OR=9.14&p=0.002, OR=1.14). In group 1, the level of IL-6 was higher.

Conclusion: Sleepiness in OSA was associated with short sleep duration, evening and no specific chronotype, increased Arousal index, and lower sleep efficacy. These findings will help to guide future research into the development of sleepiness in OSA.