The role of microsleeps to estimate sleepiness at the wheel and near-miss accidents in obstructive sleep apnea.

Study Objectives: Obstructive sleep apnea (OSA) is considered a risk factor for sleepiness at the wheel (SW) and near-miss accidents (NMA). To date, there are subjective and objective methods such as the Maintenance of Wakefulness Test (MWT) to investigate sleepiness. However, these methods have limitations. Therefore, a new analysis of the MWT was introduced based on the identification of microsleeps (MS). So, we tested MS analysis to improve the discriminative ability of MWT in recognizing individuals at risk for SW and NMA in a population with OSA.

Methods: The study was conducted on 100 naïve patients with suspected OSA referred to our Sleep Medicine Unit. All patients performed a full-standard polysomnography and MWT. The MWT was analyzed according to standard criteria, and the presence of MS episodes, the mean MS latency and the MS density (the mean absolute or relative number of MS) were assessed.

Results: Microsleeps were observed in 100% of alert or sleepy patients and 47% of the fully alert ( <0.0001). Almost 90% of patients reporting NMA showed episodes of MS during MWT. The occurrence of NMA was related to EDS, MS latency and MS density ( <0.001). The discriminative power for the NMA of MS density measures was higher than that derived from latency analysis, particularly in patients without EDS and with a simultaneous mean sleep latency >33 minutes.

Conclusions: MS analysis provides objective evidence of sleepiness and, therefore, could improve the discriminative ability of the MWT in recognizing individuals at high risk for accidents.