Figure 1. CONSORT flow diagram showing enrollment, allocation, and analysis.

Seventy-seven participants were assessed for eligibility. Thirty-five participants were excluded from participation for either not meeting the criteria (n = 4) or declining to participate (n = 31). Forty-two participants participated in the study and were randomized to either a flash sequence or continuous light exposure protocol. Of the 34 participants who were allocated randomly to the different flash sequence light exposures, 3 failed to comply with the prelaboratory sleep schedule and were excluded and 31 were randomly assigned to different sequences of light flashes. Eight participants were allocated to the continuous light exposure. All 39 participants were analyzed. Melatonin suppression values in 3 participants from the flash allocated group were aberrant and had to be excluded.