The aim of this study is to investigate next-day residual effects of tasimelteon compared with placebo and active control in healthy subjects.

Inclusion Criteria:

• Ability to provide written consent;
• Healthy subjects with no medical, psychiatric, or current sleep disorders;
• Men and women ages 21 - 55, inclusive;
• Possession of a valid driver's license ≥ 3 years with reported annual mileage ≥ 3,000 km.

Exclusion Criteria:

• Pregnancy or recent pregnancy;
• Subjects who are unable to read or speak English or French.