SESSION TYPE: Sleep Posters
PRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PM
PURPOSE: It has been suggested that sleep apnea may have an adaptive benefit, the reduction of nocturnal respiratory heat loss. On the other hand, there is a growing body of evidence that yawning may be a thermoregulatory mechanism that represents an adaptation to conditions that increase body/brain temperature, such as sleep fragmentation. Since sleep apnea and yawning are thermoregulatory mechanisms functioning towards opposite directions, we hypothesized that excessive daytime sleepiness due to sleep apnea is not characterized by excessive yawning.
METHODS: We have studied 85 consecutive subjects with excessive daytime hypersomnolence (Epworth scale≥12) who underwent a full night diagnostic polysomnography (PSG). Patients were classified as sleep apneic when their Apnea-Hypopnea Index (AHI) was ≥15 events/hour and as non-sleep apneic when their AHI was < 5 events/hour. Before PSG, all patients were asked whether they usually experience bouts of yawning from morning awakening until early evening (6 pm) after an efficient night sleep (>6 hours).
RESULTS: We discarded 12 subjects with AHI 5-14 events/hour. Fifty two subjects with hypersomnolence were diagnosed to suffer from sleep apnea syndrome (age 47±13 yo; Epworth scale 16±3; AHI 51±22), while the remaining 21 sleepy subjects had no sleep apnea (age 44±17; Epworth scale 17±3; AHI 2±1). Bouts of yawning have been reported by only 9 out of the 52 (17%) sleepy apneic patients and by 18 out of the 21 (86%, p<0.001) sleepy nonapneic patients.
CONCLUSIONS: It seems that absence of yawning bouts in a sleepy patient may predict the presence of sleep apnea syndrome as a cause of the excessive daytime sleepiness with a sensitivity of 83% and a specificity of 86%. The reason is unclear, however, it can be speculated that sleep apnea and yawning, both sharing an adaptive thermoregulatory ability towards opposite directions (heating/cooling respectively), usually do not coexist.
CLINICAL IMPLICATIONS: Our data suggest that questioning about daytime excessive bouts of yawning should be included in the recording of symptoms when taking medical history from sleepy subjects in the Sleep Clinic.
DISCLOSURE: The following authors have nothing to disclose: Epameinondas Kosmas, Silvia Dumitru, Sotirios Gyftopoulos, Ioannis Xazapis, Katerina Chronopoulou, Panos Demertzis
No Product/Research Disclosure InformationMetropolitan General Hospital, Neo Faliro, Greece