Sleep and circadian variability in people with delayed sleep-wake phase disorder versus healthy controls

Abstract

Objective/background: To compare sleep and circadian variability in adults with delayed sleep-wake phase disorder (DSWPD) to healthy controls.

Patients/methods: Forty participants (22 DSWPD, 18 healthy controls) completed a ten-day protocol, consisting of DLMO assessments on two consecutive nights, a five-day study break, followed by two more DLMO assessments. All participants were instructed to sleep within one hour of their self-reported average sleep schedule for the last four days of the study break. We analyzed the participants' wrist actigraphy data during these four days to examine intraindividual variability in sleep timing, duration and efficiency. We also examined shifts in the DLMO from before and after the study break.

Results and conclusions: Under the same conditions, people with DSWPD had significantly more variable wake times and total sleep time than healthy controls (p ≤ 0.015). Intraindividual variability in sleep onset time and sleep efficiency was similar between the two groups (p ≥ 0.30). The DLMO was relatively stable across the study break, with only 11% of controls but 27% of DSWPDs showed more than a one hour shift in the DLMO. Only in the DSWPD sample was greater sleep variability associated with a larger shift in the DLMO (r = 0.46, p = 0.03). These results suggest that intraindividual variability in sleep can be higher in DSWPD versus healthy controls, and this may impact variability in the DLMO. DSWPD patients with higher intraindividual variability in sleep are more likely to have a shifting DLMO, which could impact sleep symptoms and the optimal timing of light and/or melatonin treatment for DSWPD.

Clinical trial: Circadian Phase Assessments at Home, https://ichgcp.net/clinical-trials-registry/NCT01487252, NCT01487252.

Keywords: Circadian; Light; Sleep; Variability.

Conflict of interest statement

Conflict of interest: All authors report none.

Copyright © 2017 Elsevier B.V. All rights reserved.

Figures

Figure 1

Sleep onset times during the study break in healthy controls (left) and participants with delayed sleep-wake phase disorder (DSWPD, right). Participants were permitted to sleep at any time on Thursday night to recover from study-induced sleep deprivation. After that, on Friday through Monday nights, participants were instructed to sleep within 30 minutes of their average prestudy sleep onset and wake times. The variability in sleep onset on Friday through Monday was not significantly different between the DSWPD participants and healthy controls (p=0.30). The same symbols and colors are used for the same participants in the other figures.

Figure 2

Wake times during the study break in healthy controls (left) and participants with delayed sleep-wake phase disorder (DSWPD, right). Participants were permitted to wake at any time on Friday morning to recover from study-induced sleep deprivation. After that, on Saturday through Tuesday mornings, participants were instructed to sleep within 30 minutes of their average prestudy sleep onset and wake times. The variability in wake time on Saturday through Tuesday was significantly higher in the DSWPD participants versus healthy controls (p=0.015). The same symbols and colors are used for the same participants in the other figures.

Figure 3

Total sleep time during the study break in healthy controls (left) and participants with delayed sleep-wake phase disorder (DSWPD, right). Participants were permitted to sleep at any time on Thursday night to recover from study-induced sleep deprivation. After that, on Friday through Monday nights, participants were instructed to sleep within 30 minutes of their average prestudy sleep onset and wake times. The variability in total sleep time on Friday through Monday was significantly higher in the DSWPD participants versus healthy controls (p=0.012). The same symbols and colors are used for the same participants in the other figures.

Figure 4

Sleep efficiency (after sleep onset) during the study break in healthy controls (left) and participants with delayed sleep-wake phase disorder (DSWPD, right). Participants were permitted to sleep at any time on Thursday night to recover from study-induced sleep deprivation. After that, on Friday through Monday nights, participants were instructed to sleep within 30 minutes of their average prestudy sleep onset and wake times. The variability in sleep efficiency on Friday through Monday was not significantly different between the DSWPD participants versus healthy controls (p=0.93). The same symbols and colors are used for the same participants in the other figures.

Figure 5

The clock time of the dim light melatonin onsets (DLMOs) measured immediately before and after the 5 day study break in healthy controls (left) and participants with delayed sleep-wake phase disorder (DSWPD, right). Participants were permitted to sleep at any time on the first night of the study break, but for the remaining 4 nights participants were instructed to sleep within 30 minutes of their average prestudy sleep onset and wake times. Only 2 healthy controls but 6 DSWPD participants had more than a 1 hour shift in the DLMO. The same symbols and colors are used for the same participants in the other figures.