Clinical and Polysomnographic Correlates of Subjective Sleepiness in Mild Obstructive Sleep Apnea

The decision to treat mild obstructive sleep apnea (OSA) often hinges on the presence of subjective daytime sleepiness. This study was done to identify clinical and polysomnographic features which correlate with subjective sleepiness in mild OSA.

Utilizing data from the Apnea Positive Pressure Long-term Efficacy Study, 199 participants with mild OSA were identified. Participants were grouped as "sleepy" or "non-sleepy" based on their responses to a question regarding excessive daytime sleepiness, and Epworth Sleepiness Scores. We compared demographic, clinical and baseline polysomnographic data between the groups.

The prevalence of subjective sleepiness was 74.4%. The sleepy group was younger (46.1 ± 12.6 vs. 53.3 ± 13.1 years, p=0.001), reported lower quality of life (4.5 ± 0.69 vs. 4.9 ± 0.61, p=0.0002), had higher depression scores (5.4 ± 4.7 vs. 3.1 ± 3.5, p=0.003) and reported more naps per week (2.6 ± 2.9 vs. 1.3 ± 1.9, p=0.01). Total sleep time and sleep efficiency were notably higher in the sleepy (254.2 ± 106 vs. 220.4 ± 114 min, p=0.08) and (80.2 ± 12.6 vs. 75.7 ± 14.9 %, p=0.06), approaching statistical significance. The non-sleepy group had slightly higher apnea hypopnea index (AHI: 12.2 ± 1.5 vs. 11.2 ± 2.4 events/hour, p=0.01) and worse desaturation indices.

Subjective sleepiness in mild OSA is associated with younger age, worsened mood and quality of life. This study suggests that evidence of increased sleep drive on polysomnography may correlate with subjective sleepiness in mild OSA.