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Circadian phase resetting by a single short-duration light exposure

Rahman, S.A., St Hilaire, M.A., Chang, A.-M., Santhi, N., Duffy, J.F., Kronauer, R.E., Czeisler, C.A., Lockley, S.W. and Klerman, E.B. (2017) Circadian phase resetting by a single short-duration light exposure JCI insight, 2 (7).

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BACKGROUND. In humans, a single light exposure of 12 minutes and multiple-millisecond light exposures can shift the phase of the circadian pacemaker. We investigated the response of the human circadian pacemaker to a single 15-second or 2-minute light pulse administered during the biological night. METHODS. Twenty-six healthy individuals participated in a 9-day inpatient protocol that included assessment of dim light melatonin onset time (DLMO time) before and after exposure to a single 15-second (n = 8) or 2-minute (n = 12) pulse of bright light (9,500 lux; 4,100 K fluorescent) or control background dim light (<3 lux; n = 6). Phase shifts were calculated as the difference in clock time between the two phase estimates. RESULTS. Both 15-second and 2-minute exposures induced phase delay shifts [median (± SD)] of -34.8 ± 47.2 minutes and -45.4 ± 28.4 minutes, respectively, that were significantly (P = 0.04) greater than the control condition (advance shift: +22.3 ± 51.3 minutes) but were not significantly different from each other. Comparisons with historic data collected under the same conditions confirmed a nonlinear relationship between exposure duration and the magnitude of phase shift. CONCLUSIONS. Our results underscore the exquisite sensitivity of the human pacemaker to even short-duration single exposures to light. These findings may have real-world implications for circadian disruption induced by exposure to brief light stimuli at night. TRIAL REGISTRATION. The study was registered as a clinical trial on, NCT #01330992. FUNDING. Funding for this study was provided by NSBRI HFP02802 and NIH P01-AG09975, R01-HL114088 (EBK), RC2-HL101340-0 (EBK, SWL, SAR, REK), K02-HD045459 (EBK), K24-HL105664 (EBK), T32-HL07901 (MSH, SAR), HL094654 (CAC), and AG044416 (JFD). The project described was supported by NIH grant 1UL1 TR001102-01, 8UL1TR000170-05, UL1 RR 025758, Harvard Clinical and Translational Science Center, from the National Center for Advancing Translational Science.

Item Type: Article
Authors :
Rahman, S.A.
St Hilaire, M.A.
Chang, A.-M.
Santhi, N.
Duffy, J.F.
Kronauer, R.E.
Czeisler, C.A.
Klerman, E.B.
Date : 2017
DOI : 10.1172/jci.insight.89494
Depositing User : Clive Harris
Date Deposited : 17 Jun 2020 01:00
Last Modified : 17 Jun 2020 01:00

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