TY - JOUR
T1 - Phase angle of entrainment in morning- and evening-types under naturalistic conditions
AU - Emens, Jonathan S.
AU - Yuhas, Krista
AU - Rough, Jennifer
AU - Kochar, Nidhi
AU - Peters, Dawn
AU - Lewy, Alfred J.
N1 - Funding Information:
The research was supported by grants from the Public Health Service: K23RR017636 to JSE; R01 EY018312-09A1, R01 HD42125, and R01 AG21826 to AJL; and MO1 RR000334 and UL1 RR024120 to Oregon Health & Science University and the Oregon Clinical and Translational Research Institute, respectively. Dr. Emens is also supported by the Sleep Research Society Foundation Gillin Award and a NARSAD Young Investigator Award.
PY - 2009/4
Y1 - 2009/4
N2 - Differences in morningness-eveningness among humans are commonly ascribed to circadian parameters, such as circadian period and responsivity to environmental time cues, as well as homeostatic sleep drive. Light is the primary synchronizer of the human biological clock, and if circadian differences exist between morning and evening types, they should have different phase angles of entrainment to the light/dark cycle; that is, morning and evening types should have different patterns of light exposure relative to endogenous circadian phase (ECP). When phase angle of entrainment is strictly defined as the relationship between a marker of ECP and the timing of light exposure, such differences have been demonstrated in the laboratory under controlled light/dark cycles and have recently been shown under conditions of spring and summer light exposure outside the laboratory, taking into account the variable intensity of light. Here, we report similar results from a large (n=66), diverse cohort of morning and evening types across the age span studied at all different times of the year. Differences between morning and evening types in light exposure relative to ECP, indicative of a difference in the phase angle of entrainment to the external light/dark cycle, were found. Specifically, evening types, compared to morning types, had a higher ratio of phase advancing to phase delaying by light. We interpret this as indicating a longer circadian period () in evening types.
AB - Differences in morningness-eveningness among humans are commonly ascribed to circadian parameters, such as circadian period and responsivity to environmental time cues, as well as homeostatic sleep drive. Light is the primary synchronizer of the human biological clock, and if circadian differences exist between morning and evening types, they should have different phase angles of entrainment to the light/dark cycle; that is, morning and evening types should have different patterns of light exposure relative to endogenous circadian phase (ECP). When phase angle of entrainment is strictly defined as the relationship between a marker of ECP and the timing of light exposure, such differences have been demonstrated in the laboratory under controlled light/dark cycles and have recently been shown under conditions of spring and summer light exposure outside the laboratory, taking into account the variable intensity of light. Here, we report similar results from a large (n=66), diverse cohort of morning and evening types across the age span studied at all different times of the year. Differences between morning and evening types in light exposure relative to ECP, indicative of a difference in the phase angle of entrainment to the external light/dark cycle, were found. Specifically, evening types, compared to morning types, had a higher ratio of phase advancing to phase delaying by light. We interpret this as indicating a longer circadian period () in evening types.
KW - Circadian
KW - Human
KW - Light
KW - Melatonin
KW - Morningness-eveningness
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U2 - 10.1080/07420520902821077
DO - 10.1080/07420520902821077
M3 - Article
C2 - 19360491
AN - SCOPUS:67651183694
SN - 0742-0528
VL - 26
SP - 474
EP - 493
JO - Chronobiology International
JF - Chronobiology International
IS - 3
ER -