Late bedtimes prevent circadian phase advances to morning bright light in adolescents

ABSTRACT

We examined phase shifts to bright morning light when sleep was restricted by delaying bedtimes. Adolescents (n = 6) had 10-h sleep/dark opportunities for 6 days. For the next 2 days, half were put to bed 4.5 h later and then allowed to sleep for 5.5 h (evening room light + sleep restriction). The others continued the 10-h sleep opportunities (sleep satiation). Then, sleep schedules were gradually shifted earlier and participants received bright light (90 min, ~6000 lux) after waking for 3 days. As expected, sleep satiation participants advanced (~2 h). Evening room light + sleep restriction participants did not shift or delayed by 2–4 h.

Abbreviations: DLMO: dim light melatonin onset.

KEYWORDS:

• Circadian rhythms
• DLMO
• adolescent
• evening light
• entrainment
• bright light
• phase shift
• sleep
• sleep deprivation
• phase response curve to light

Acknowledgements

We are grateful to Victoria Tomaka, Anna Kathryn Ishikawa, Ieva Misiunaite, Andrew Kalweit, Samantha Evans, Jennifer Austiff, Elizabeth DiMaggio, John Glines and Sabrina Velez for their assistance with data collection.

Disclosure Statement

The authors report no conflicts of interest. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NHLBI. The NHLBI had no involvement in designing the study, data collection, data analysis and interpretation, writing of the manuscript or in the decision to submit the manuscript for publication. The authors alone are responsible for the content and writing of the paper. S.J. Crowley had full access to all data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Additional information

Funding

This work was supported by a grant from the National Heart, Lung, and Blood Institute (NHLBI) (R01 HL105395) awarded to S.J.C.