17.1 Habitual Heavy Alcohol Drinking in Healthy Adults Is Associated With Reduced Circadian Photoreceptor Responsivity to Light

ObjectivesHabitual alcohol consumption and circadian timing are connected. Studies have found that heavy alcohol use is associated with eveningness. Only 2 studies have assessed dim light melatonin onset (DLMO) in the context of habitual alcohol use, and both reported that a shorter DLMO-midsleep interval was associated with heavier alcohol use. A gap in this research is the potential impact of alcohol use on the circadian photoreceptor and the intrinsically photosensitive retinal ganglion cells, which influence circadian timing. This study compared sleep, circadian timing, and photoreceptor responsivity between light and heavy alcohol drinkers.MethodsParticipants were healthy (average age = 27 years) and included 28 light (average 2.6 drinks/week) and 50 heavy (average 17.9 drinks/week) drinkers. They participated in an 8-day study protocol: 1 week of ad lib sleep with wrist actigraphy, followed by a 9-hour lab session with a photoreceptor responsivity (postillumination pupil response, PIPR) and circadian phase assessment. Participants passed a breathalyzer test at the start of the lab session.ResultsBoth drinking groups were good sleepers with minimal mood disturbance. Consistent with earlier studies, the heavy drinkers had more eveningness (p = .029) and a trend for a shorter DLMO-midsleep interval (p = .059) as compared to the light drinkers. The PIPR in the heavy drinkers was significantly smaller than in the light drinkers (p = .006), suggesting reduced circadian photoreceptor responsivity in the heavy drinkers. In the light drinkers, a larger PIPR in the evening, reflecting greater sensitivity to phase-delaying light, was significantly associated with a later DLMO (r = 0.42; p = .028). However, this relationship was absent in the heavy drinkers (r = -0.07; p = .68).ConclusionsThe findings replicate previous work examining the relationship between chronotype, DLMO, and habitual alcohol consumption. For the first time, circadian photoreceptor responsivity was examined and found to be significantly reduced in heavy drinkers as compared to light drinkers. This finding is consistent with prior rodent studies that found reduced phase shifts to light with acute or chronic alcohol consumption, and suggests that habitual heavy alcohol use may impair the circadian response to light in humans.ALC, SLP, SUD ObjectivesHabitual alcohol consumption and circadian timing are connected. Studies have found that heavy alcohol use is associated with eveningness. Only 2 studies have assessed dim light melatonin onset (DLMO) in the context of habitual alcohol use, and both reported that a shorter DLMO-midsleep interval was associated with heavier alcohol use. A gap in this research is the potential impact of alcohol use on the circadian photoreceptor and the intrinsically photosensitive retinal ganglion cells, which influence circadian timing. This study compared sleep, circadian timing, and photoreceptor responsivity between light and heavy alcohol drinkers. Habitual alcohol consumption and circadian timing are connected. Studies have found that heavy alcohol use is associated with eveningness. Only 2 studies have assessed dim light melatonin onset (DLMO) in the context of habitual alcohol use, and both reported that a shorter DLMO-midsleep interval was associated with heavier alcohol use. A gap in this research is the potential impact of alcohol use on the circadian photoreceptor and the intrinsically photosensitive retinal ganglion cells, which influence circadian timing. This study compared sleep, circadian timing, and photoreceptor responsivity between light and heavy alcohol drinkers. MethodsParticipants were healthy (average age = 27 years) and included 28 light (average 2.6 drinks/week) and 50 heavy (average 17.9 drinks/week) drinkers. They participated in an 8-day study protocol: 1 week of ad lib sleep with wrist actigraphy, followed by a 9-hour lab session with a photoreceptor responsivity (postillumination pupil response, PIPR) and circadian phase assessment. Participants passed a breathalyzer test at the start of the lab session. Participants were healthy (average age = 27 years) and included 28 light (average 2.6 drinks/week) and 50 heavy (average 17.9 drinks/week) drinkers. They participated in an 8-day study protocol: 1 week of ad lib sleep with wrist actigraphy, followed by a 9-hour lab session with a photoreceptor responsivity (postillumination pupil response, PIPR) and circadian phase assessment. Participants passed a breathalyzer test at the start of the lab session. ResultsBoth drinking groups were good sleepers with minimal mood disturbance. Consistent with earlier studies, the heavy drinkers had more eveningness (p = .029) and a trend for a shorter DLMO-midsleep interval (p = .059) as compared to the light drinkers. The PIPR in the heavy drinkers was significantly smaller than in the light drinkers (p = .006), suggesting reduced circadian photoreceptor responsivity in the heavy drinkers. In the light drinkers, a larger PIPR in the evening, reflecting greater sensitivity to phase-delaying light, was significantly associated with a later DLMO (r = 0.42; p = .028). However, this relationship was absent in the heavy drinkers (r = -0.07; p = .68). Both drinking groups were good sleepers with minimal mood disturbance. Consistent with earlier studies, the heavy drinkers had more eveningness (p = .029) and a trend for a shorter DLMO-midsleep interval (p = .059) as compared to the light drinkers. The PIPR in the heavy drinkers was significantly smaller than in the light drinkers (p = .006), suggesting reduced circadian photoreceptor responsivity in the heavy drinkers. In the light drinkers, a larger PIPR in the evening, reflecting greater sensitivity to phase-delaying light, was significantly associated with a later DLMO (r = 0.42; p = .028). However, this relationship was absent in the heavy drinkers (r = -0.07; p = .68). ConclusionsThe findings replicate previous work examining the relationship between chronotype, DLMO, and habitual alcohol consumption. For the first time, circadian photoreceptor responsivity was examined and found to be significantly reduced in heavy drinkers as compared to light drinkers. This finding is consistent with prior rodent studies that found reduced phase shifts to light with acute or chronic alcohol consumption, and suggests that habitual heavy alcohol use may impair the circadian response to light in humans.ALC, SLP, SUD The findings replicate previous work examining the relationship between chronotype, DLMO, and habitual alcohol consumption. For the first time, circadian photoreceptor responsivity was examined and found to be significantly reduced in heavy drinkers as compared to light drinkers. This finding is consistent with prior rodent studies that found reduced phase shifts to light with acute or chronic alcohol consumption, and suggests that habitual heavy alcohol use may impair the circadian response to light in humans.