Previous studies reported that physical activity could buffer the negative association of psychological stress with affective wellbeing. However, the studies that examined this relation in everyday life have assessed physical activity only by self-report but not with objective measures such as accelerometry. We therefore investigated the associations of both subjectively and objectively measured physical activity with stress experiences and affective wellbeing. A total of 90 university students participated in a 10-day experience sampling and diary study during their examination period and reported about stress experiences, physical activity, and affective states. Physical activity was additionally assessed using accelerometry in 50 of the participants. Subjectively assessed physical activity and objectively assessed light physical activity were associated with feeling less stressed in the evening. Also, light physical activity during the day was associated with a smaller increase/higher decrease in feeling stressed from morning to evening. The association of stress experience with negative affect was moderated by objective light physical activity. No interactive effects of stress intensity and physical activity on affective wellbeing were found. On stressful days, physical activity may buffer the negative association between stress and affective wellbeing. Particularly light physical activity as assessed with accelerometry seems to play an important role. It may be beneficial for students' affective wellbeing to increase or at least maintain physical activity during examination periods.

Heart rate variability has been found to be related to emotional processing and emotional responses. Studies that investigated these relationships were mostly lab-based or cross-sectional. Only limited research used intensive longitudinal data, in particular investigating within-individual processes in real-life settings. This study addresses the applicability of ambulatory-assessed electrocardiograms in combination with the experience sampling methodology by investigating the associations of various HRV measures with affective states on within- and between-individual levels. A total of 26 participants aged 18–29 years (23 females) wore electrocardiograms continuously for seven days. The participants received seven prompts per day and answered questions about their affective wellbeing. The heart rate and heart rate variability measures differed between body positions and activity classes. The heart rate and ratio of low-to-high-frequency heart rate variability were consistently associated with positive affect on a within-individual (state-like) level. These associations were mainly driven by the items of feeling “enthusiastic” and “happy”. No associations were found with negative affect. Overall, we found evidence that the dominance of the sympathetic nervous system over the parasympathetic nervous system was associated with higher levels of positive affect on a within-individual (state-like) level. Suggestions for the application of ambulatory electrocardiogram assessment in the study of the association between autonomous nervous system activity and ecological momentary assessment-based variables are discussed.

Summary: This study aims to investigate the temporal links between physical activity, sleep and affective wellbeing in young adults. In particular, the aim was to examine whether physical activity is associated with sleep indicators in subsequent nights and, in turn, whether sleep was associated with improved affective wellbeing the next morning. Relatedly, moderation by baseline levels of depressive symptoms, sleep quality, habitual physical activity and gender was analysed. One‐hundred and forty‐seven individuals (85.7% female) aged 18–25 years old participated in an experience sampling study over 14 consecutive days. Participants received seven prompts per day, and answered questions about their physical activity and affective states. Every morning, participants also reported their sleep. Physical activity throughout the day was not related to sleep during the following night or to affective wellbeing the next morning. An exception to that pattern was that physical activity before 14:00 hours was associated with longer subsequent sleep duration. Better subjective sleep quality predicted affective wellbeing the next morning. Associations of physical activity, sleep and affective wellbeing were not moderated by baseline depressive symptoms, sleep quality or habitual physical activity. However, investigation of gender as a moderator revealed that moderate physical activity was associated with better subsequent sleep quality for males, but not for females. Overall, we found that physical activity is associated with better subsequent sleep for males, but not for females. Also, our study provides further evidence that better sleep quality is associated with the next morning's affective wellbeing.

Physical activity and being outdoors both improve affective well-being. However, little is known about the synergistic effects between them and the influences of contextual factors such as the life domain of physical activity (work-, chores-, leisure, or sports-related) or the type of the outdoor environment (green space, blue space, or city area) on mood. This study investigates the synergistic effects of physical activity and being outdoors as well as the potential role of contextual factors on mood. A total of 158 individuals aged 18–25 years (133 females) participated in a 14-day experience sampling study. Participants received seven prompts per day and answered questions about their physical activity, contextual factors, and affective well-being. Physical activity and being outdoors were associated with concurrent higher levels of positive and lower levels of negative affect compared to being physically inactive or being indoors, respectively. However, no synergistic effects were found. Being outdoors in a city area was associated with a less positive and more negative affect than being in nature. Work- and chores-related physical activity was associated with less positive affect and more negative affect compared to sports- or leisure-related physical activity. To foster positive affect, people should schedule leisure-related physical activity in nature.

Summary: Pre‐sleep worrying is associated with sleep disturbance, which in turn is associated with impaired affective wellbeing. However, studies examining the fine‐grained temporal order of these variables are still lacking. In particular, within‐person mediation of the association between pre‐sleep worrying and the following day's affective wellbeing by subjective and objective indicators of sleep has not been tested yet. This study investigates the extent to which pre‐sleep worrying predicts positive/negative affect the following day, and whether subjective/objective sleep disturbances are possible mediators for this relationship. Data from two experience sampling studies were pooled for the analyses, resulting in a total sample of 220 participants aged between 18 and 30 years ( M = 23.2 years, SD = 2.8). The hypotheses were tested at both the between‐ and within‐subject level using causal mediation analysis. The within‐subject analyses revealed partial mediation of the relationship between pre‐sleep worrying and positive as well as negative affect the next day by subjective sleep quality. By contrast, sleep as measured by actigraphy appears not to be relevant for the link between pre‐sleep worrying and affective wellbeing the following day. Baseline levels of depressive symptoms and sleep disturbances did not moderate the associations between pre‐sleep worrying, sleep indices and affective states the following day. Improving perceived sleep quality by addressing pre‐sleep worrying could be a potential avenue to enhance affective wellbeing and promote better mental health in young adults.

Low self-esteem and repetitive negative thinking are associated with higher burnout risk among university students at the between-person level. However, there is increasing evidence that associations identified in between-person analyses do not always reflect processes occurring within individuals. Therefore, we conducted a four-week ecological momentary assessment study with N = 96 students during an examination period. Results showed that higher self-esteem was followed by feeling less burnt out on a within-day and day-to-day level. Also, higher self-esteem was followed by lower repetitive negative thinking (i.e., rumination on the within-day level and pre-sleep worry on the day-to-day level), which in turn was followed by feeling less burnt out. Mediation analyses showed that a substantial proportion of the associations between self-esteem and feeling burnt out was mediated by repetitive negative thinking at both the within- and between-person level. In addition, we also found evidence of a reverse temporal sequence. Higher levels of burnout were followed by an increase in repetitive negative thinking, which in turn led to lower self-esteem. Finally, self-esteem instability partially moderated the associations of self-esteem and subsequent pre-sleep worry and burnout at the within-person but not between-person level. These findings imply that there may be a bidirectional relationship between self-esteem, repetitive negative thinking, and burnout, indicating a possible vicious cycle that could perpetuate psychological distress. Future studies should examine these dynamics more closely to better understand their causal interplay and implications for intervention.