Noun
an inability to stay awake
Source: WordNetPhysiological changes caused by cocaine withdrawal include vivid and unpleasant dreams, insomnia or hypersomnia, increased appetite and psychomotor retardation or agitation. Source: Internet
For example, the first week of September is Idiopathic Hypersomnia Awareness Week, a worldwide event dedicated to educating people about idiopathic hypersomnia, a rare neurological sleep disorder. Source: Internet
Types * Dyssomnias - A broad category of sleep disorders characterized by either hypersomnia or insomnia. Source: Internet