Protocol diagram.

<p>Time of day at the top is Chicago time, and time of day on the bottom is Kenyan time (9-h later than Chicago time). Study day is shown on the left. Black shading shows timing of scheduled sleep periods. Schedules were individualized for each participant to best match their habitual sleep times. This diagram shows the protocol for a participant on a 00:00–08:00 baseline sleep schedule. Days 1–4 were baseline during which participants remained on local, Chicago time (as indicated on the left). On days 6–9 the sleep schedule was shifted 9-h earlier (advanced) as though participants had traveled to Kenya, and the wall clocks in the bedrooms were changed to indicate the shifted, Kenyan time. During baseline days the sleep schedule was aligned with each participant’s circadian rhythms, whereas during advanced days the sleep schedule was misaligned. “X” shows the timing of the Automated Neuropsychological Assessment Metrics (ANAM) performance battery and “Px” shows the timing of practice ANAM tests. Tests were given relative to each participants scheduled sleep times; 2 h after waking, and then every 3 h with a total of 5 tests per day. Light grey shading shows the timing of circadian phase assessments, during which the dim light melatonin onset (DLMO) was assessed.