Efficacy Study of EVT 201 to Treat Insomnia

Inclusion Criteria: * must have a diagnosis of primary insomnia * over the last three months, must have a normal bedtime of between 9 pm and 1 am and a time in bed of at least 7 hours * must be able to attend the Sleep Center for two consecutive nights on four occasions over a two month period * must be willing and able to complete a sleep diary and questionnaires Exclusion Criteria: * must not have a clinically significant or unstable medical condition that may interfere with sleep * must not have a major psychiatric disorder (other than insomnia) such as depression, schizophrenia, bipolar disorder * must not be currently using any medication know to affect sleep e.g. hypnotics, anxiolytics,antidepressants, antihistamines, anticonvulsants * must not intentionally nap 3 (or more) times per week * must not smoke more than 10 cigarettes per day and /or be able not to smoke without distress or discomfort for the duration of visits to the sleep laboratory ( i.e. approximately 12 hours)