Excessive daytime sleepiness refers to the inability to stay alert during the major awake period of the day, resulting in you falling asleep at inappropriate times.

When sleepiness interferes with daily routines and activities, or reduces your ability to function, it is considered excessive.

This is a prevalent condition. In Singapore, the prevalence of excessive daytime sleepiness has been reported to be 9 percent (Ng TP et al, Sleep Medicine 2005).