Excessive daytime sleepiness (or EDS) is a medical condition where people often feel sleepy during the day, even though they had enough sleep at night. EDS occurs with many sleep disorders. It is a defining feature of some sleep disorders such as narcolepsy, sleep apnea or Circadian rhythm sleep disorder. EDS is difficult to treat without knowing its causse. There are certain drugs that can help with EDS. In general, many treatments of the underlying disease (which causes the sleepiness) will also take into account EDS. The drugs which can treat EDS are usually stimulants.