The main symptom of excessive sleepiness is a pathological need for sleep during the day despite enough sleep time at night. Often, it is accompanied by a need for extended sleep time at night. The hallmark of excessive sleepiness is repeated bouts of napping during the day, often at inappropriate times. These naps come on suddenly and the person may feel powerless to prevent it. They rarely provide any relief and tend to continue throughout the day. The sleepiness is often accompanied by changes in mood and cognition such as anxiety, irritability, decreased energy, restlessness, slow thinking and speech, loss of appetite, hallucinations, and memory difficulty. These changes along with the tendency to nap at inappropriate times can have a negative impact on a person’s ability to hold a job and maintain social and familial obligations.