Search

Eight high-school girls participating in competitive sports and six nonparticipating girl's living north of the polar circle recorded their sleep once a week during the Fall, including the period when the sun does not rise above the horizon. Sleep-quality scores were computed as the sum of answers identical to a preset 'right' answer indicating good sleep-quality. Significant differences on sleep-quality between the two groups were found, but a significant influence of amount of daylight or exercise could not be confirmed. When sleep-quality was ranked during three periods through the Fall, the girls participating in competitive sports showed a trend of increasing sleep-quality and the nonparticipants a decreasing one. An explanation based on influence of exercise thresholds upon sleep-quality is presented.

A survey in a high school in the city of Tromso in the spring of 1988 was designed to examine the characteristics of sleep and factors promoting and disturbing sleep. Out of 621 students 465 (74.9%) responded to 11 questions about last night's sleep and what the individual perceived as usual sleep (10 questions). On this information two sleep-quality scores, a special score for last night's sleep and a general score for what is perceived as usual sleep, were computed. The sleep-quality score was the sum of answers identical to a preset 'right' answer indicating good sleep-quality. Multiple regression analyses separately by sex showed that different variables influence sleep-quality of boys and girls. Activity and intensity of exercise were taken into the regression model for the special sleep-score for boys but not for girls. For girls psychological factors seemed of greater importance to sleep-quality than exercise.

Long-distance dog sled races, e.g. Iditarod (Alaska) and Finnmarksløpet (Northern Norway), are extremely demanding sporting events that might expose mushers, handlers and a large number of organisers and volunteers to risks for their health. The purpose of this systematic literature review (PROSPERO registration n. CRD42017069136) was to identify and summarise all available scientific literature relative to health issues connected to participating in these races. Using a literature search strategy in line with PRISMA guidelines, 117 scientific studies, sought through databases (Google Scholar and PubMed, between 2nd and 9th May 2017) and scrutiny of reference lists, were screened. Studies published in English treating any health issues assessed during or after a long-distance dog sled race were included, with no restriction in relation to their study design or the characteristics of participants studied. The quality of the studies was assessed using a standardised checklist. Ten studies met the criteria for being included in a qualitative analysis. The data synthesis showed that participants underwent strenuous psychophysical load, with insufficient sleep/rest and inadequate energy intake. Findings on hydrations are mixed. The risk of incurring in life-threatening injuries or infections was low, although injuries and infections of minor severity were common. No alterations of blood markers were observed from before to after the races. These findings will help planning prevention and treatment strategies in long-distance dog sled races. However, more research is needed in this field in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: Stress and mental fatigue are major health threats to employees in office-based occupations. Physical activity is widely used as a stress-management intervention for employees. Moreover, experiences in contact with nature have been shown to provide stress-reduction and restoration from mental fatigue. OBJECTIVES: In a pilot study designed as a randomized controlled trial we investigated the impact of a green-exercise intervention on psychological and physiological indicators of stress in municipality employees. METHODS: Fourteen employees (7 females and 7 males, 49±8 yrs) volunteered in an exercise-based intervention in workplace either outdoors in a green/nature area or in an indoor exercise-setting. The intervention consisted of an information meeting and two exercise sessions, each including a biking bout and a circuit-strength sequence using elastic rubber bands (45-minutes, at about 55% of HR reserve, overall). Main outcomes were perceived environmental potential for restoration, affective state, blood pressure (BP) and cortisol awakening response (CAR AUCG and CAR AUCI) and cortisol levels in serum. Measurements were taken at baseline and in concomitance with the exercise sessions. Furthermore, affective state and self-reported physical activity levels were measured over a 10-weeks follow-up period. RESULTS: Compared with the indoor group, the nature group reported higher environmental potential for restoration (p < 0.001) and Positive Affect (p < 0.01), along with improved CAR AUCI (p = 0.04) and, marginally, diastolic BP (p = 0.05). The nature group also reported higher ratings of Positive Affect at follow-up (p = 0.02). Differences at post-exercise were not found for any of the other components of affective state, systolic BP, CAR AUCG and cortisol levels measured in serum. CONCLUSIONS: Green-exercise at the workplace could be a profitable way to manage stress and induce restoration among employees. Further studies on larger samples are needed in order to improve the generalizability of the results. [ABSTRACT FROM AUTHOR]

Several studies have shown the differences among chronotypes in the circadian rhythm of different physiological variables. Individuals show variation in their preference for the daily timing of activity; additionally, there is an association between chronotype and sleep duration/sleep complaints. Few studies have investigated sleep quality during the week days and weekends in relation to the circadian typology using self-assessment questionnaires or actigraphy. The purpose of this study was to use actigraphy to assess the relationship between the three chronotypes and the circadian rhythm of activity levels and to determine whether sleep parameters respond differently with respect to time (weekdays versus the weekend) in Morning-types (M-types), Neither-types (N-types) and Evening-types (E-types). The morningness-eveningness questionnaire (MEQ) was administered to 502 college students to determine their chronotypes. Fifty subjects (16 M-types, 15 N-types and 19 E-types) were recruited to undergo a 7-days monitoring period with an actigraph (Actiwacth® actometers, CNT, Cambridge, UK) to evaluate their sleep parameters and the circadian rhythm of their activity levels. To compare the amplitude and the acrophase among the three chronotypes, we used a one-way ANOVA followed by the Tukey-Kramer post-hoc test. To compare the Midline Estimating Statistic of Rhythm (MESOR) among the three chronotypes, we used a Kruskal-Wallis non-parametric test followed by pairwise comparisons that were performed using Dunn's procedure with a Bonferroni correction for multiple comparisons. The analysis of each sleep parameter was conducted using the mixed ANOVA procedure. The results showed that the chronotype was influenced by sex (χ2 with p = 0.011) and the photoperiod at birth (χ2 with p < 0.05). Though the MESOR and amplitude of the activity levels were not different among the three chronotypes, the acrophases compared by the ANOVA post-hoc test were significantly different ( p < 0.001). The ANOVA post-hoc test revealed the presence of a significant difference ( p < 0.001) between the M-types (14:32 h) and E-types (16:53 h). There was also a significant interaction between the chronotype and four sleep parameters: Sleep end, Assumed Sleep, Immobility Time and Sleep Efficiency. Sleep Efficiency showed the same patterns as did Assumed Sleep and Immobility Time: the Sleep Efficiency of the E-types was poorer than that of the M- and N-types during weekdays (77.9% ± 7.0 versus 84.1% ± 4.9 and 84.1% ± 5.2) but was similar to that measured in the M- and N-types during the weekend. Sleep Latency and Movement and Fragmentation Index were not different among the three chronotypes and did not change on the weekend compared with weekdays. This study highlights two key findings: first, we observed that the circadian rhythm of activity levels was influenced by the chronotype; second, the chronotype had a significant effect on sleep parameters: the E-types had a reduced sleep quality and quantity compared with the M- and N-types during weekdays, whereas the E-types reached the same levels as the other chronotypes during the weekends. These findings suggest that E-types accumulate a sleep deficit during weekdays due to social and academic commitments and that they recover from this deficit during 'free days' on the weekend. [ABSTRACT FROM AUTHOR]

The replenishment of blood glucose after exercise was studied in 62 healthy subjects performing a standardized exercise at 2 different times of the day in 5 different months of the year. Blood samples (fingertip) for glucose determination were drawn at the start of exercise and at 1, 5, 10 and 30 min after exercise. The total area under the glucose—time curves during the 30 min of recovery was calculated in either absolute units or as percent of the starting value. ANOVAs, with and without glucose variables from the exercise span as covariates, tested the integrated glucose—time areas for the effect of sex, time of day, and season. Exercise in the morning showed best recovery at all times of the year and females showed best recovery at each test time. In spite of significant time effects, a correlation between glucose recovery and amount of daylight could not be established. Significant differences in recovery between months, times of day and sexes were greatly influenced by glucose levels at start of the exercise, which showed a yearly rhythm. [ABSTRACT FROM AUTHOR]

Investigates the response of blood glucose to exercise throughout the year in an environment with large differences in the amount of daylight. Calculation of the total area under the glucose-time curves; Use of the analysis of variance method; Comparison of exercise between mornings and afternoons.

Background: An individual's chronotype influences his or her physiological rhythms. Some studies have looked at the effect of time of day on the responses to exercise, but studies on the effect of long-term training are lacking. Objective: To report the effects of an 8-week training period during the polar night in nonathletes of different chronotypes living at 70°N. Design: In all, 10 morning (M), 10 neither (N) and 10 evening (E) types were recruited, and their aerobic capacity (VO2max), strength, flexibility and balance before and after the training period were tested. Results: 3 E-types, 5 N-types and 6 M-types completed the protocol. An increase in VO2max and strength was observed for the whole group. The best negative correlation (r=-0.5287) was found between the Morningness-Eveningness Questionnaire (MEQ) score and the increase in VO2max, and the best positive correlation (r=0.4395) was found between MEQ and the increase in strength. Changes in balance and flexibility did not show any clear trends. Conclusion: In an environment with no outdoor daylight, it seems that the response to 8 weeks of aerobic training is larger in the E-than in the M-types, although the M-types showed a larger improvement in strength. [ABSTRACT FROM AUTHOR]

Magnetic storms trigger myocardial infarctions with mechanisms relating to heart rate variability. Solar cycle-to-solar cycle differences and solar cycle stage dependence shown herein may resolve prior controversy and serve to advocate coordinated worldwide systematically aligned biological and physical monitoring. * This paper was originally invited by the historian-geophysicist Wilfried SCHRöDER of Bremen, Germany, for his biographical "Encounters," and is to serve as an update on the project on the BIOsphere and the Cosmos (BIOCOS) and its offspring ICEHRV (Dr. Kuniaki Otsuka's International Chronome Ecologic Study of Heart Rate Variability). It is intended for distribution at a NATO conference on space weather hazards, organized by Dr. Ioannis Daglis, June 18-29, 2000.