Efficacy Study of EVT 201 in the Treatment of Elderly Patients With Daytime Sleepiness

Inclusion Criteria: * Diagnosis of primary insomnia according to DSM-IV * Over the last three months for at least 5 nights per week, must have a normal bedtime of between 9 pm and 1 am and a time in bed of at least 7 hours * A history of sleepiness, tiredness or unintentional napping during the daytime attributed to to poor sleep at night * Able to attend the Sleep Center for five nights (two consecutive nights on two occasions and one night on one occasion)over a five week period * Willing and able to complete a sleep diary and questionnaires Exclusion Criteria: * Clinically significant or unstable medical condition that may interfere with sleep * Major psychiatric disorders (other than insomnia) such as depression, schizophrenia, bipolar disorder * History of myocardial infarction, cardiac failure or clinically significant dysrhythmias in the previous 2 years or clinically significant ECG abnormalities at screening * History of substance abuse * Disorders that interfere with drug pharmacokinetics * History of cancer, except basal cell carcinoma * Use of hypnotics, anxiolytics, antidepressants, anticonvulsants, over-the-counter sleep aids, histamine-1 receptor antagonists (except for loratadine and fexofenadine), beta-adrenergic blockers (except for atenolol), respiratory stimulants and decongestants, systemic steroids, narcotic analgesics, any other compound which might impact sleep-wake function, or medication used for the treatment of Parkinson's disease such as dopamine agonists and L-dopa (e.g., Sinemet, Madopar or Requip) * Use of hypnotics within the 2 weeks preceding the Screening Period or within five half-lives of the medication, whichever is longer * Consuming ≥ 350 mg per day of xanthine-containing food or beverages * Smoking ≥ 10 cigarettes per day and/or unable to refrain from smoking without distress or discomfort for the duration of visits to the sleep laboratory (i.e.≥ 20 hours) * Body mass index \> 34 kg/m2; * Performing night work or rotating shift work during the past month * Traveling across \> 3 time zones in the past 2 weeks * Participation in another trial of an investigational product or device within the previous 30 days * Known allergy or sensitivity to benzodiazepines