[Circadian rhythm : Influence on Epworth Sleepiness Scale score]

Area of Science:

• Sleep Medicine
• Chronobiology

Background:

• The Epworth Sleepiness Scale (ESS) is a common tool for assessing daytime sleepiness in patients with sleep-disordered breathing.
• The influence of circadian rhythm-induced alertness levels on ESS scores remains unclear.

Purpose of the Study:

• To investigate how circadian rhythm-dependent alertness affects Epworth Sleepiness Scale (ESS) scores.
• To determine if ESS is a reliable measure of sleepiness irrespective of daily alertness variations.

Main Methods:

• A monocentric prospective study involving 97 patients with suspected sleep-disordered breathing.
• Sleepiness was assessed using the Epworth Sleepiness Scale (ESS), Karolinska Sleepiness Scale (KSS), and Stanford Sleepiness Scale (SSS) at multiple time points before and after polysomnography and CPAP titration.
• Measurements captured intra-daily and inter-daily variations in alertness.

Main Results:

• Karolinska Sleepiness Scale (KSS) and Stanford Sleepiness Scale (SSS) scores showed a circadian pattern, with increased sleepiness at noon and evening.
• Sleepiness scores increased after a diagnostic polysomnography night but decreased in the morning after CPAP titration.
• Epworth Sleepiness Scale (ESS) scores were not significantly altered by intra-daily or inter-daily changes in alertness levels.

Conclusions:

• The Epworth Sleepiness Scale (ESS) is a dependable tool for assessing daytime sleepiness.
• ESS performance is independent of the circadian rhythm-dependent level of alertness.
• This supports the consistent use of ESS in clinical practice for sleep-disordered breathing patients.