VEC-162

Total sleep time during the first 2/3 of the night following an 8-hour phase advance bedtime, as measured by PSG. This is representative of trans meridian travel across 8 time zones.

Treatment-emergent adverse events will be summarized by presenting the number and percentage of patients having any treatment-emergent AE, having an AE in each body system, and having each individual AE.

Entrainment is a measure of synchronization of the master body clock to the 24-hour day. The circadian period (τ) was calculated using urinary aMT6s collected over four separate 48 hour periods, approximately 1 week apart, during the run-in and randomized phases of the trial. Maintenance of entrainment is defined as the proportion of subjects who become non-entrained to a 24 hour day after randomization to tasimelteon or placebo. Non-entrainment was defined as having a post-baseline τ value ≥ 24.1 or the lower bound of the 95% CI \>24.0.

Entrainment is a measure of synchronization of the master body clock to the 24-hour day. The circadian period (τ) was calculated using urinary aMT6s collected over four 48 hour periods , collected approximately 1 week apart for 4 separate weeks, during the screening and month 1 of the randomization phase of the trial. Entrainment was defined as having a post-baseline τ value less than 24.1 and a 95% CI that included 24.0.

Clinical response is defined as the coincident demonstration of entrainment (aMT6) and a score ≥ 3 on the Non-24 Clinical Response Scale (N24CRS). N24CRS measures improvement in sleep-wake measures and overall functioning (LQ-nTST, UQ-dTSD, MoST and CGI-C). Each assessment is scored as a 1 or 0 depending on the pre-specified threshold (see below). LQ-nTST: \>45 minutes increase in average nighttime sleep duration; UQ-dTSD: \>45 minutes decrease in average daytime sleep duration; MoST: \>30 minutes increase and a standard deviation \<2 hours during double-masked phase (6 months); CGI-C: \<2.0 from the average of D112 and Day 183 compared to baseline For patients randomized to tasimelteon 20 mg and who also participated in the screening phase of Study 3203 (month 7 of treatment), the screening τ from Study 3203 was used if the patient did not become entrained in Study 3201 but did become entrained during the screening phase of Study 3203.

Average latency to persistent sleep is defined as the length of time elapsed between lights off and onset of persistent sleep (defined as the point at which 10 minutes of uninterrupted sleep has begun as determined by PSG) between Baseline and the average of nights 1 and 8.

The average improvement in Latency to persistent sleep (the number of minutes between Lights Off and the onset of at least 10 minutes of persistent sleep, as measured by polysomnography) is defined as the difference observed in the VEC-162 treated subjects compared with placebo treated subjects.

Measured using polysomnography (PSG) and analyzed as change from baseline. Examination of the observational phase baseline data demonstrated that Night 3 was the night most disrupted.

Hamilton Rating Scale for Depression (HAM-D) assesses the range of symptoms that are most frequently observed in subjects with major depressive disorder (MDD) on a scale from 0 to 52. Higher HAM-D scores indicate more severe levels of depressive symptoms, thus, a negative change from baseline indicates a reduction (or improvement) in depressive symptoms.

Exposure response to VEC-162 on induction of circadian phase shift as measured by Dim Light Melatonin Onset (DLMO) was defined as the time change between Night 3 and Night 4 when melatonin production reached 25% of the maximum melatonin concentration. Samples below LOQ of the melatonin assay were assigned 5 pg/ml.

Exposure response was measured by comparing the change in sleep efficiencies of VEC-162 and placebo treated subjects upon a sleep schedule phase advance. Sleep efficiency (total time asleep divided by the time allowed as an opportunity for sleep in a period multiplied by 100%, where time allowed for sleep was 8 hours or 480 minutes) was measured objectively by overnight polysomnographic recordings. Sleep efficiency was also compared in parts of the night by dividing the full night into thirds.

To assess plasma concentrations and pharmacokinetics of tasimelteon in subjects with mild or moderate hepatic impairment compared to healthy subjects with normal hepatic function.