Table 1. Circadian phase marked by the DLMO, the estimated Tmin,^a and scheduled sleep times.

	Placebo			0.5 mg melatonin			3.0 mg melatonin
	Mean		SD (h)	Mean		SD (h)	Mean		SD (h)
Phase advance of DLMO (h)	1.7		0.7	2.5b		0.7	2.6b		0.3
Shift/day (min)c		34			50			52
Baseline
DLMO	21:41		1.0	21:25		1.2	21:51		0.8
Bedtime	24:04		0.8	24:04		0.7	24:05		0.6
Wake time	8:04		0.8	8:04		0.7	8:05		0.6
Estimated Tmin	4:41		1.0	4:25		1.2	4:51		0.8
Tmin to wake interval (h)	3.4		0.9	3.6		1.2	3.2		0.7
Treatment d 1
Tmin to wake interval (h)	2.4		0.9	2.6		1.2	2.2		0.6
Treatment d 3
Bedtime	21:04		0.8	21:04		0.7	21:05		0.6
Wake time	5:04		0.8	5:04		0.7	5:05		0.6
Estimated Tmina	3:34		1.3	2:47		1.0	3:06		0.9
Tmin to wake interval (h)	1.5		1.0	2.3		0.9	2.0		0.7
Final
DLMO	20:01		1.4	18:58		1.0	19:14		0.9
Estimated Tmina	3:01		1.4	1:58		1.0	2:14		0.9

^aCalculated by adding 7 h to the DLMO.

^bSignificantly different from placebo (P < 0.01).

^cCalculated by dividing cumulative phase advance of DLMO after 3 treatment days by 3.