Flash intensity and duration

These data were obtained by having individuals participate in a series of 16-day studies, each with a 34-hour in-laboratory period. In this between-subjects design, we examined phase shifting in response to variable-intensity (3-9500 photopic lux) flashes at fixed duration (2 ms; n=28 participants) and variable-duration (10 μs-10 s) flashes at fixed intensity (2000 photopic lux; n=31 participants) for 1 hour with 15 s between flashes . Acute melatonin suppression, objective alertness, and subjective sleepiness during the flash sequence were also assessed. 

Methods
Melatonin phase shifting data were obtained during constant routine. Saliva samples were collected and later assessed for melatonin concentrations with a commercially-available ELISA (Salimetrics) based on a monoclonal melatonin antibody.

Melatonin suppression, objective alertness (median reaction time on an auditory psychomotor vigilance test), and subjective sleepiness data (Stanford Sleepiness Scale) were obtained immediately before and after a 1-hour light exposure.