Effect of bright light therapy on delayed sleep/wake cycle and reaction time of athletes participating in the Rio 2016 Olympic Games.

This study investigated the effect of using an artificial bright light on the entrainment of the sleep/wake cycle as well as the reaction times of athletes before the Rio 2016 Olympic Games. A total of 22 athletes from the Brazilian Olympic Swimming Team were evaluated, with the aim of preparing them to compete at a time when they would normally be about to go to bed for the night. During the 8-day acclimatization period, their sleep/wake cycles were assessed by actigraphy, with all the athletes being treated with artificial light therapy for between 30 and 45 min (starting at day 3). In addition, other recommendations to improve sleep hygiene were made to the athletes. In order to assess reaction times, the Psychomotor Vigilance Test was performed before (day 1) and after (day 8) the bright light therapy. As a result of the intervention, the athletes slept later on the third (p = 0.01), seventh (p = 0.01) and eighth (p = 0.01) days after starting bright light therapy. Regarding reaction times, when tested in the morning the athletes showed improved average (p = 0.01) and minimum reaction time (p = 0.03) when comparing day 8 to day 1. When tested in the evening, they showed improved average (p = 0.04), minimum (p = 0.03) and maximum reaction time (p = 0.02) when comparing day 8 to day 1. Light therapy treatment delayed the sleep/wake cycles and improved reaction times of members of the swimming team. The use of bright light therapy was shown to be effective in modulating the sleep/wake cycles of athletes who had to perform in competitions that took place late at night.

Intermittent Short Sleep Results in Lasting Sleep Wake Disturbances and Degeneration of Locus Coeruleus and Orexinergic Neurons.

STUDY OBJECTIVES: Intermittent short sleep (ISS) is pervasive among students and workers in modern societies, yet the lasting consequences of repeated short sleep on behavior and brain health are largely unexplored. Wake-activated neurons may be at increased risk of metabolic injury across sustained wakefulness. METHODS: To examine the effects of ISS on wake-activated neurons and wake behavior, wild-type mice were randomized to ISS (a repeated pattern of short sleep on 3 consecutive days followed by 4 days of recovery sleep for 4 weeks) or rested control conditions. Subsets of both groups were allowed a recovery period consisting of 4-week unperturbed activity in home cages with littermates. Mice were examined for immediate and delayed (following recovery) effects of ISS on wake neuron cell metabolics, cell counts, and sleep/wake patterns. RESULTS: ISS resulted in sustained disruption of sleep/wake activity, with increased wakefulness during the lights-on period and reduced wake bout duration and wake time during the lights-off period. Noradrenergic locus coeruleus (LC) and orexinergic neurons showed persistent alterations in morphology, and reductions in both neuronal stereological cell counts and fronto-cortical projections. Surviving wake-activated neurons evidenced persistent reductions in sirtuins 1 and 3 and increased lipofuscin. In contrast, ISS resulted in no lasting injury to the sleep-activated melanin concentrating hormone neurons. CONCLUSIONS: Collectively these findings demonstrate for the first time that ISS imparts significant lasting disturbances in sleep/wake activity, degeneration of wake-activated LC and orexinergic neurons, and lasting metabolic changes in remaining neurons most consistent with premature senescence.

Exposure to bright light during evening class hours increases alertness among working college students.

OBJECTIVE: To evaluate the effects of exposure to bright light on sleepiness during evening hours among college students. METHODS: Twenty-seven healthy college students, all males, with ages ranging from 21 to 24years, working during the day and studying in the evening, participated in this study. During the 3week study, the students wore actigraphs and recorded levels of sleepiness. In a crossover design, on the second and third weeks, the students were exposed to bright light (BL) at either 19:00 or 21:00h. Salivary melatonin samples were collected before and after BL exposure. ANOVA test for repeated measurements were performed. RESULTS: After BL exposure, sleepiness levels were reduced at 20:30 and 22:00h (F=2.2; p<0.05). ANOVA showed statistical differences between time (F=4.84; p=0.04) and between day and time of BL exposure (F=4.24; p=0.05). The results showed effects of melatonin onset at 20:00 and 21:30h and sleepiness levels (F=7.67; p=0.02) and perception of sleepiness and intervention time (F=6.52; p=0.01). CONCLUSION: Controlled exposure to BL during evening hours increased alertness among college students. The effects of BL on sleepiness varied according to the time of melatonin onset.