This study is the first, to our knowledge, to systematically examine the time course of recovery of alertness from the chronic EDS in patients diagnosed with OSAS and treated with CPAP The achievement of functional levels of daytime alertness only after repeated nights of normal sleep may be of critical importance in clinical decisions involving this patient population. The pervasive EDS associated with OSAS is not only a debilitating condition, but it may have fatal consequences. Several studies have suggested that physiologic sleepiness is a common and poorly understood factor in automobile accidents. There has been widespread anecdotal speculation that the EDS associated with OSAS places these patients at a higher risk for motor vehicle mishaps. One study has attempted a carefully controlled inquiry comparing the driving records of patients with diagnosed OSAS with normal control subjects. The patients with sleep apnea were seven times more likely to have had an automobile accident than the subjects without sleep apnea. This has important implications for physicians making decisions concerning restrictions of occupational activities and motor vehicle operation for sleepy OSAS patients. The findings of the present study may be used to specify minimum durations of treatment with CPAP before OSAS patients should be allowed to resume regular activities.
Further research is indicated to determine the exact point between one and 14 nights of CPAP treatment that will result in a return of functional alertness. These studies must utilize the MSLT and take into consideration the individual variations of basal levels of sleepiness. It may be that 14 nights are actually many more than the minimum required for any patient to alleviate EDS, and the actual number for a given patient may depend on the basal level of sleepiness.