| Autor: |
Melanie Rüger, George C. Brainard, Charles A. Czeisler, Sat Bir S. Khalsa, Melissa A. St. Hilaire, Richard E. Kronauer, Steven W. Lockley |
| Rok vydání: |
2012 |
| Předmět: |
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| Zdroj: |
The Journal of Physiology. 591:353-363 |
| ISSN: |
0022-3751 |
| DOI: |
10.1113/jphysiol.2012.239046 |
| Popis: |
The photic resetting response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase response curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18-30 years) were studied for 9-10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 I¼W cm-2, 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of -2.6 h and 1.3 h, respectively. The 480 nm PRC induced â�¼75% of the response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure. © 2012 The Physiological Society. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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