Excessive daytime sleepiness(without a known cause).Depression, anxiety, stress, and boredom are commonly thought to cause excessive sleepiness.
Until the 1950s, most people thought of sleep as a passive, dormant part of our daily lives. We now know that our brains are very active during sleep. Moreover, sleep affects our daily functioning and our physical and mental health in many ways that we are just beginning to understand.
by Anna March 30, 2005