Table 1.
Melatonin responses to room light vs. dim light in study 1 (n = 104)
| Median (25%, 75%) |
|||
|---|---|---|---|
| Light (<200 lux), d 2-3 | Dim (<3 lux), d 3-4 | Dim (<3 lux), d 4-5 | |
| MLT onset (h min) | 23 39 (22 18, 00 55) | 21 54 (20 58, 23 14)a | 22 09 (21 13, 23 21)a,b |
| MLT offset (h min) | 08 16 (07 20, 09 34) | 08 23 (07 12, 09 22) | 08 26 (07 17, 09 30)b |
| MLT duration (h) | 8.75 (8.25, 9.42) | 10.28 (9.68, 10.85)a | 10.13 (9.68, 10.60)a |
| Phase angle MLT onset (h) | 0.38 (−0.32, 1.22) | 1.95 (1.37, 2.63)a | 1.68 (1.07, 2.45)a,b |
| Phase angle MLT offset (h) | −8.52 (−8.92, −7.55) | −8.33 (−8.87, −7.50) | −8.38 (−8.87, −7.77)b |
Melatonin (MLT) outcomes are reported for participants over three consecutive days. Individuals lived in room light (<200 lux) and slept in darkness until midway through d 3 (column 2). Over the next 24 h, participants lived in dim light (<3 lux) and slept in darkness (column 3), followed by a constant routine procedure on d 4 and 5 conducted in under 3 lux light (column 4). Phase angle is defined as the relative timing of melatonin onset or offset vs. scheduled bedtime. A positive phase angle indicates that the event happened before scheduled sleep, whereas negative values indicate that the event happened after bedtime.
Significant differences for comparisons with the first melatonin cycle (column 2; d 2-3)
Significant differences for comparisons with the second melatonin cycle (column 3; d 3-4).