SM-1 vs 2 Comparators and Placebo in Participants With a History of Transient Insomnia.

Inclusion Criteria: * Signed written consent form. * Experienced at least 1 prior episode of transient insomnia meeting all of the following criteria: difficulty falling asleep or staying asleep; next day impairment or distress associated with the disturbed sleep; frequency of 1 to 7 nights per week; duration of less than 1 month or more than 1 month of intermittent episodes. * Routinely spends 6.5 - 9.5 hours in bed each night, with bed time varying no more than 2 hours over a week. Potential participants will be required to complete a paper diary for a minimum of 7 days during the screening period, with at least 5 entries completed over the 7 days. * Body Mass Index (BMI) between 19 and 32 kg/m2. * Good general health, as determined by a thorough medical, sleep and psychiatric history review, brief physical examination including vital sign measurements, and an assessment of screening laboratory test results. * Female subjects of childbearing potential must be using an acceptable method of contraception during the study and for the 30 days following the last dose of study drug, and must have a negative urine pregnancy test at every study visit. Female subjects of non-childbearing potential are not required to use contraception if they have been surgically sterilized or are post-menopausal as defined by the cessation of menses for a period of at least 2 years before screening. * Male subjects must use an acceptable method of contraception during the study and for the 30 days…