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Circadian phase delay using the newly developed re-timer portable light device

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Abstract

Appropriately timed exposure to bright light has been shown to phase shift the circadian rhythm and alleviate associated sleeping difficulties. This study evaluated the effectiveness of a newly developed re-timer portable light device for phase delaying the circadian rhythm. Participants included 12 healthy, good sleepers (M = 32.3 years, SD = 12.5, male = 5). A repeated measures counterbalanced design was used to assess circadian phase delay following the use of either the re-timer or no device on two consecutive evenings. Outcome measures included dim light melatonin onset (DLMO), subjective sleepiness, and adverse effects of the re-timer. Analyses revealed a significant phase delay of DLMO following use of the re-timer (M = 46 min, SD = 76 min) on two consecutive evenings when compared to no light control (M = 3 min, SD = 81 min; p = .016). There was a trend for evening subjective sleepiness to decrease after using the re-timer compared to no light control, however this trend was not statistically significant. Adverse effects of the re-timer were headache, eye irritation, and light bothersome to eyes, however these were not severe and treatment was not requested or required. The re-timer device is an effective method of delaying the circadian rhythm in good sleepers.

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Authors and Affiliations

  1. Adelaide Institute for Sleep Health, Repatriation General Hospital, Flinders University Centre for Research Excellence, Flinders University, GPO Box 2100, Adelaide, SA, 5001, Australia

    Nicole Lovato

  2. School of Psychology, Flinders University of South Australia, Bedford Park, Adelaide, SA, 5001, Australia

    Leon Lack

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  1. Nicole Lovato
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  2. Leon Lack
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Correspondence to Nicole Lovato.

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Conflict of interest

LL is a stock shareholder in the company RE-Time, PTY. LTD and was involved in the development of the re-timer device. NL has no conflict of interest to disclose. RE-Time, PTY. LTD provided the re-timer devices used in this study.

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Lovato, N., Lack, L. Circadian phase delay using the newly developed re-timer portable light device. Sleep Biol. Rhythms 14, 157–164 (2016). https://doi.org/10.1007/s41105-015-0034-6

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  • DOI: https://doi.org/10.1007/s41105-015-0034-6

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