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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.

Secretion of the hormone melatonin shows a circadian rhythm and is inhibited by light. Light therapy with phase shifting of the melatonin rhythm has been used as treatment of sleeping problems and seasonal affective disorders (SAD). Exercise has also been shown to suppress the melatonin secretion. In order to investigate the effect of increased level of habitual physical activity upon melatonin secretion in areas with extreme short days and high level of midwinter insomnia, 18 high school students participated in this study. Their habitual physical activity throughout two consecutive falls were recorded. The following January, blood samples were taken for melatonin analyses from 1530h to 2300h. After the fall with highest habitual activity level, the plasma melatonin showed significantly decreased values at all sampling times compared to values after lowest level of activity. The relative increase in melatonin level at 2300h, however, tended to be of a greater magnitude after the fall with highest activity cornpared to the fall with Iowest activity (p=.094). A change in habitual level of activity should be thought of as a possible help for treating midwinter insomnia and SAD.

This is an Accepted Manuscript of an article published by Taylor & Francis in Chronobiology International on 28 June 2018, available online: http://www.tandfonline.com/10.1080/07420528.2018.1475395. Rhythms can be observed at all levels of the biologic integration in humans. The observation that a biological or physiological variable shows a circadian rhythm can be explained by several multifactorial systems including external (exogenous), internal (endogenous) and psychobiological (lifestyle) mechanisms. Our body clock can be synchronized with the environment by external factors, called “synchronizers”, i.e. the light–dark cycle, but it is also negatively influenced by some pathological conditions or factors, called “chronodisruptors,” i.e. aging or low physical activity (PA). The desynchronization of a 24-h rhythm in a chronic manner has been recently defined “chronodisruption” or “circadian disruption.” A very large number of hormonal variables, such as adrenal and gonadal stress steroids, are governed by circadian rhythmicity. Such hormones, in normal conditions, show a peak in the first part of the day, while their typical diurnal fluctuations are totally out of sync in subjects affected by cancer or metabolic diseases, such as obesity, diabetes and metabolic syndrome. In general, a flatter slope with altered peaks in cortisol and testosterone circadian rhythms has been observed in pathological individuals. PA, specifically chronic exercise, seems to play a key role as synchronizer for the whole circadian system in such pathologies even if specific data on steroids circadian pattern are still sparse and contradictory. Recently, it has been proposed that low-intensity chronic PA could be an effective intervention to decrease morning cortisol levels in pathological subjects. The standardization of all confounding factors is needed to reach more clear evidence-based results.