Exposure to Bright Light Modifies HRV Responses to Mental Tasks during Nocturnal Sleep Deprivation

Abstract

This study was intended to determine the effects of continuous bright light exposure on cardiovascular responses, particularly heart rate variability (HRV), at rest and during performance of mental tasks with acute nocturnal sleep deprivation. Eight healthy male subjects stayed awake from 21.00 to 04.30 hours under bright (BL, 2800 lux) or dim (DL, 120 lux) light conditions. During sleep deprivation, mental tasks (Stroop color-word conflict test: CWT) were performed for 15 min each hour. Blood pressure, electrocardiogram, respiratory rate, urinary melatonin concentrations and rectal temperature were measured. During sleep deprivation, BL exposure depressed melatonin secretion in comparison to DL conditions. During sleep deprivation, exposure to BL delayed the decline in heart rate (HR) for 4 h in resting periods. A significant increment of HR induced by each CWT was detected, especially at 03.00 h and later, under DL conditions only. In addition, at 04.00 h, an index of sympathetic activity and sympatho-vagal balance on HRV during CWT increased significantly under DL conditions. In contrast, an index of parasympathetic activity during CWT decreased significantly under DL conditions. However, the indexes of HRV during CWT did not change throughout sleep deprivation under BL conditions. Our results suggest that BL exposure not only delays the nocturnal decrease in HR at rest but also maintains HR and balance of cardiac autonomic modulation to mental tasks during nocturnal sleep deprivation.

Sleep-Wake Differences in Heart Rate Variability During a 105-Day Simulated Mission to Mars

“…It is known that light is the dominant environmental input affecting circadian rhythms ( 14 ). Sympathetic activity during the day increases with light color temperature ( 26 ) and light intensity ( 27 ). In this regard, the loss of sympathetic predominance reported herein may be associated with a prolonged exposure to the artifi cial environmental light of the isolation facility, of lower intensity and color temperature than natural light.…”

An assessment of the relevance of laboratory and motorcycling tests for investigating time of day and sleep deprivation influences on motorcycling performance

“…The limited sample size is justified by the homogeneity between subjects related to their expertise level in motorcycling. Moreover, this sample size conforms to those used in many recent studies focused on the effects of sleep deprivation (Curcio et al, 2003;Bambaeichi et al, 2005;Yokoi et al, 2006).…”

Diurnal Variation and Twenty-Four Hour Sleep Deprivation Do Not Alter Supine Heart Rate Variability in Healthy Male Young Adults

“…However, we did not control for the amount of light exposure from screens (e.g., television) that the participants used during sleep deprivation. Although more research on the effects of light exposure on HRV during sleep deprivation is needed, several studies compared the effects of bright and dim light exposure on indices of parasympathetic activity at rest and found no differences [ 83 , 84 ]. Thus, it is possible but unlikely that the potentially varying light exposure from the TV among our participants substantially affected their HF-HRV data.…”