A Short Nap and Natural Bright Light Exposure Improve Positive Mood Status

National Institute of Occupational Safety and Health, Kanagawa, Japan.
Industrial Health (Impact Factor: 1.12). 04/2007; 45(2):301-8. DOI: 10.2486/indhealth.45.301
Source: PubMed


While the effects of a short nap on performance and arousal level have been well investigated, less attention has been paid to its effects on mood status. The aim of the present study was to examine the effects of a short nap and natural bright light exposure on mood status. Participants were 16 healthy females who were on average 38.1 (SD = 2.68) yr old. From 11:00 to 12:00, the participants carried out a set of tasks twice with baseline lighting (<100 lux). From 12:40 to 13:10, they were subjected to three experimental conditions: control (<100 lux), natural bright light (>2,000 lux), and a 20-min nap. From 13:10 to 16:10, the tasks were repeated six times with the baseline lighting. To measure mood status, multiple visual analogue scales (to measure anxiety, sadness, anger, confusion, apathy, fatigue, and sleepiness) and the Mood Check List 3 (MCL-3) (to derive "pleasantness", "satisfaction" and "relaxation") were employed. The results showed that brief (30 min) natural bright light exposure improved one dimension of mood status, "pleasantness". A short nap also improved dimensions of mood status ("pleasantness", "satisfaction", and "relaxation"). These results suggest that the proper application of both natural light and a short nap shifts the mood status to the positive/favorable side.

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    • "The combination of bright light exposure and caffeine intake may scale down melatonin secretion (hormone associated with sleep) and increase alertness, body temperature and performance after having sleep deprivation in the previous night (Wright et al. 2000). There are even suggestions that short duration of bright light exposure after midday napping can help prevent sleep inertia (Phipps-Nelson et al. 2003), improve mood stability, alertness and performance (Kaida et al. 2007), and even beneficial for social interaction and job satisfaction at the workplace (Judge and Ilies 2004). However, there is no consensus on bright light effects since there is also a report that emotional stability and sleepiness are worsened with only the exposure to bright light (Burgess et al. 2002). "
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    ABSTRACT: Napping/siesta during the day is a phenomenon, which is widely practised in the world. However, the timing, frequency, and duration may vary. The basis of napping is also diverse, but it is mainly done for improvement in alertness and general well-being. Neuroscience reveals that midday napping improves memory, enhances alertness, boosts wakefulness and performance, and recovers certain qualities of lost night sleep. Interestingly, Islam, the religion of the Muslims, advocates midday napping primarily because it was a practice preferred by Prophet Muhammad (pbuh). The objectives of this review were to investigate and compare identical key points on focused topic from both neuroscientific and Islamic perspectives and make recommendations for future researches.
    Journal of Religion and Health 08/2015; DOI:10.1007/s10943-015-0093-7 · 1.02 Impact Factor
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    • "In other words, we hypothesized that participants would feel more vital when they had experienced relatively more light. We had, however, no clear hypotheses concerning the relationship between light exposure with tension, positive and negative affect as e in contrast to potential activating effects -earlier findings on affective improvements under bright light have been inconsistent (e.g., Baron, Rea, & Daniels, 1992; Daurat et al., 1993; Hubalek et al., 2010; Kaida, Takahashi, & Otsuka, 2007; Partonen & Lönnqvist, 2000; Smolders et al., 2012). As earlier laboratory-based experiments have revealed time and mental status-dependent effects during daytime (e.g., Smolders et al., 2012; Vandewalle et al., 2006), we also investigate whether the relationship between light exposure and vitality is equally strong throughout the day, or whether instead it depends on time of day, or on previous vitality level. "
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    ABSTRACT: In the current study, we investigated daily light exposure and its relation with vitality in everyday settings on an hour-to-hour basis. The method consisted of experience sampling combined with continuous light measurement and a sleep diary during three consecutive days. Data collection was distributed over a full year. Results revealed substantial inter- and intra-individual differences in hourly light exposure. The amount of light experienced was significantly related to vitality, indicating that persons who were exposed to more light experienced more vitality, over and above the variance explained by person characteristics, time of day, activity patterns and sleep duration during the previous night. This relationship was more pronounced in the morning, during the darker months of the year and when participants had experienced relatively low vitality during the previous hour. Overall, the results provide support for acute effects of light exposure on feelings of vitality during daytime, even in everyday life.
    Journal of Environmental Psychology 12/2013; 36:270–279. DOI:10.1016/j.jenvp.2013.09.004 · 2.40 Impact Factor
    • "This area of research could be advanced by including selected cognitive measures concurrently with fatigue and energy state measures.[77] A final concern is that several potential moderators could not be considered, including biological sex,[78] variations in exposure to bright light resulting from indoor versus outdoor exercise,[79] and variations in sleepiness resulting from the prior night's sleep or daytime naps.[80] Understanding the effect of acute exercise on energy and fatigue is also limited in part because of inadequate reporting of physical activity history as well as the dimensions of the acute exercise stimulus (intensity, duration , mode). "
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    ABSTRACT: You can access full text of the article here: Background: Studies examining acute exercise effects on energy and fatigue levels have not been quantitatively summarized. Purpose: To estimate the population effects of a single bout of exercise on energy and fatigue states and examine potential moderators. Methods: Google Scholar and MEDLINE were searched systematically for published studies that measured changes in energy and fatigue after acute exercise. Meta-analytic techniques were used to analyze 58 energy effects and 58 fatigue effects from the same 16 studies involving 678 participants. Most studies involved 21–40 minutes of moderate-intensity aerobictype exercise. Result: The homogeneous mean effect for energy was Δ = 0.47 (95% confidence interval [CI] = 0.39, 0.56). The heterogeneous mean effect for fatigue was Δ = 0.03 (95% CI = −0.08, 0.13). The fatigue effect was moderated by a three-way interaction between change in feelings of energy, exercise intensity, and exercise duration. Conclusion: Acute exercise enhances feelings of energy. Decreases in fatigue occur only when post-exercise increases in energy are at least moderately large after low-to-moderate intensity exercise lasting longer than 20 minutes. Future research should focus on short-duration (<15 minutes), vigorous-intensity exercise and long-duration (>40 minutes) exercise in non-student groups.
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