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The aim of this study was to investigate sleep‐wake behavior and gain insights into perceived impairment (sleep, fatigue, and cognitive function) of athletes competing in two international multi‐day adventure races. Twenty‐four athletes took part across two independent adventure races: Queensland, Australia and Alaska, USA. Individual sleep periods were determined via actigraphy, and racers self‐reported their perceived sleep disturbances, sleep impairment, fatigue and cognitive function. Each of these indices was calculated for pre‐, during‐ and post‐race periods. Sleep was severely restricted during the race period compared to pre‐race (Queensland, 7:46 [0:29] vs. 2:50 [1:01]; Alaska, 7:39 [0:58] vs. 2:45 [2:05]; mean [SD], hh:mm). As a result, there was a large cumulative sleep debt at race completion, which was not ‘reversed’ in the post‐race period (up to 1 week). The deterioration in all four self‐reported scales of perceived impairment during the race period was largely restored in the post‐race period. This is the first study to document objective sleep‐wake behaviors and subjective impairment of adventure racers, in the context of two geographically diverse, multi‐day, international adventure races. Measures of sleep deprivation indicate that sleep debt was extreme and did not recover to pre‐race levels within 1 week following each race. Despite this objective debt continuing, perceived impairment returned to pre‐race levels quickly post‐race. Therefore, further examination of actual and perceived sleep recovery is warranted. Adventure racing presents a unique scenario to examine sleep, performance and recovery. [ABSTRACT FROM AUTHOR]

The timing, intensity, and duration of exposure to both artificial and natural light have acute metabolic and physiological effects in mammals. Recent research in human adults suggests exposure to moderate intensity light later in the day is concurrently associated with increased body mass; however, no studies have investigated the effect of light exposure on body mass in young children. We examined objectively measured light exposure and body mass of 48 preschool-aged children at baseline, and measured their body mass again 12 months later. At baseline, moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI). Increased duration of light exposure at baseline predicted increased BMI 12-months later, even after controlling for baseline sleep duration, sleep timing, BMI, and activity. The findings identify that light exposure may be a contributor to the obesogenic environment during early childhood. [ABSTRACT FROM AUTHOR]