key: cord-0852466-o5v1wls3 authors: Dai, Wenjuan; Zhou, Jieying; Li, Guangming; Zhang, Bin; Ma, Ning title: Maintaining normal sleep patterns, lifestyles and emotion during the COVID‐19 pandemic: The stabilizing effect of daytime napping date: 2021-01-08 journal: J Sleep Res DOI: 10.1111/jsr.13259 sha: 0aea320a2aaae9f633d4dfac6ee0532a26ab2099 doc_id: 852466 cord_uid: o5v1wls3 This study aimed to assess changes in sleep pattern and their influence on people's daily life and emotion during the COVID‐19 pandemic. Self‐developed questionnaires were used to measure changes in nocturnal sleep, daytime napping, lifestyles and negative emotions in individuals before and after the COVID‐19 pandemic. Nine hundred and thirty effective questionnaires were collected in this study. Repeated measures analysis of variance and hierarchical regression analysis were applied. We found that individuals' sleep rhythms were delayed, and sleep duration and sleep latency were increased during the stay‐at‐home orders. Meanwhile, their exercise levels and learning/working efficiency were decreased, and electronic device use time, annoyance levels and anxiety levels were increased. Delayed sleep patterns affected lifestyles and emotions. Moreover, sleep quality positively predicted learning/working efficiency and exercise levels, and negatively predicted use of electronic devices and negative emotions. Sleep patterns became delayed on weekdays during stay‐at‐home orders in all four daytime napping groups (no daytime napping, daytime napping as before, more daytime napping and less daytime napping), and the group taking daytime naps as before had a minimal variation, and their lifestyles and emotions were significantly better than those of the other groups. This study demonstrated that under the influence of stress caused by the pandemic, maintaining regular daytime napping was an effective way to stabilize sleep patterns and biological rhythms, keep good lifestyles and alleviate the effect of acute psychological stress, and to prevent and control mental disorders during the pandemic. responses that affected people's sleep, lifestyles and emotions. Stress is a state of threatened homeostasis (physical or perceived threat to homeostasis). In this state, adaptive compensatory responses by the organism might be activated to sustain homeostasis (Pacák & Palkovits, 2001) . Psychological stress occurs when individuals perceive that environmental demands tax or exceed their adaptive capacity (Cohen et al., 1995 (Cohen et al., , 2007 , which can trigger stress responses in many areas, such as emotions (e.g., fear, anger, helplessness and hopelessness), cognitions (e.g., confusion, dissociation, difficulty concentrating, etc.), physiological responses (e.g., insomnia, increased heart rate, anxiety, fatigue, etc.) and interpersonal relationship issues (e.g., suspicion, isolation, sense of abandonment, etc.) (Friedman, 2015) . Studies have shown that public health emergencies, such as the severe acute respiratory syndrome (SARS) and the 2009 H1N1/influenza A epidemics, caused acute stress responses in people, which generated negative emotions (e.g., fear, anxiety and anger) (Bai et al., 2004; Carmona et al., 2016; Tam et al., 2004; Yu et al., 2005) . Stress also affects sleep, including sleep-wake patterns, wake after sleep onset (WASO) and sleep architecture, by affecting the activation of the hypothalamic-pituitary-adrenal (HPA) axis (Lo Martire et al., in press; Sanford et al., 2014) . Recent findings demonstrated that during COVID-19, individuals experienced changes in sleep patterns, such as delayed sleep phases, increased sleep duration and poor sleep quality when staying at home (Cellini et al., 2020; Wright et al., 2020) . In contrast to nocturnal sleep, daytime napping usually lasts from 15 min to 2 h (Dinges, 1989 ). An appropriate nap can not only reduce the level of subjective and objective sleepiness but also improve cognitive function and behavioural performance, such as short-term memory and emotional control (Brooks & Lack, 2006; Evans et al., 1977; Jones, 2009; Tietzel & Lack, 2001) . Although daytime napping might be beneficial, long naps lead to sleep inertia, which affects subsequent cognitive and emotional functions. In addition, long naps negatively affect the duration and pattern of nocturnal sleep (ÅKerstedt et al., 1989) . People's schedules would be more flexible at home during the COVID-19 pandemic, providing conditions for daytime napping or alterations in daytime napping time. Previous studies on daytime napping mainly focused on the effects of napping and factors that influence it, but paid less attention to individual differences in daytime napping and daily performance and nocturnal sleep. Young adulthood (or early adulthood) is when individuals have the greatest energy and strong contradiction and stress (Levinson, 1986) . Young adults, especially people aged 18-25 years, are in a maturing stage of their physiological and psychological development. They are in the process of stabilizing their career and life. However, they have to face social, emotional and life challenges and change, and their strengths and vulnerabilities continue to emerge (Wood et al., 2018) . However, COVID-19 has suddenly posed a threat to young adults' stability and they may exhibit strong stress responses to emergencies and emergency-caused changes, thus causing significant changes to their sleep, lifestyles and emotions. The present study focused on alterations in young adults' nocturnal sleep, daytime napping, lifestyle and negative emotions before and after the COVID-19 pandemic. This study proposed the following hypotheses. (a) Compared to before the COVID-19 pandemic, individuals' exercise and learning/working efficiency might be worse. A total of 1,136 questionnaires were collected. After excluding unqualified questionnaires (67 out of the age range and 139 incomplete), 930 questionnaires were included in the final analysis. The valid response rate was 81.9%. The survey was internet based and investigated sleep, lifestyle and negative emotion among healthy Chinese young adults (18-35 years old) (see Table 1 ). The study was approved by the Ethics Committee of South China Normal University and was conducted from late March to April 2020. This questionnaire was developed to assess people's physical and mental conditions under stay-at-home orders during the COVID-19 pandemic. There were 25 items about sleep, lifestyle and negative emotion. There were eight items about wake-up time and time of falling asleep on weekdays and weekends before and after the pandemic. Participants needed to indicate the actual wake-up time and time of falling asleep, not the time for getting up and going to bed. To facilitate statistical analysis, for the item "Before the pandemic, what time did you usually fall asleep on weekdays?", if the time of falling asleep exceeded midnight (24:00 PM), 24 h was added to indicate that the time was the next day. The participants' original data were converted into an hour unit (e.g., 24.25 h represents 00:15). Sleep duration on weekdays and weekends before and after the pandemic was calculated based on wake-up times and times of falling asleep. There were four items about sleep duration on weekdays and weekends before and after the pandemic. Participants were asked to provide the time they needed from going to bed or putting down their phones to actually fall asleep. Sleep quality was assessed with a single item that asked respondents for the degree of change in their sleep quality during the stay-athome orders (compared with that before the pandemic). A 5-point Likert-type scale was used: 1 = substantially worsened, 2 = slightly worsened, 3 = basically unchanged, 4 = slightly improved and 5 = substantially improved. Changes in daytime napping between before and after the pandemic were assessed with a single item evaluated on a 4-point scale: 1 = no daytime napping, 2 = daytime napping as before, 3 = more daytime napping than before and 4 = less daytime napping than before. Changes in sleep patterns between before and after the pandemic were obtained by subtracting the sleep conditions before the pandemic from the sleep conditions during the stay-at-home order. For example, the difference between wake-up times on weekdays before and after the pandemic was obtained by subtracting the wakeup times on weekdays before the pandemic from the wake-up times on weekdays during the stay-at-home order. The same method was used to obtain the differences between wake-up times on weekends, time falling asleep on weekdays, time falling asleep on weekends, sleep duration on weekdays, sleep duration on weekends, sleep latency on weekdays and sleep latency on weekends. For lifestyle, three items were used to evaluate changes in exercise levels, learning/working efficiency and using electronic devices before and after the pandemic. A 5-point Likert-type scale was used for exercise level and learning/working efficiency: 1 = substantially worsened, 2 = slightly worsened, 3 = basically unchanged, 4 = slightly improved and 5 = substantially improved. A 5-point Likert-type scale was used for time using electronic devices: 1 = substantially reduced, 2 = slightly reduced, 3 = basically unchanged, 4 = slightly increased and 5 = substantially increased. For negative emotion, seven items were used to evaluate changes in subjective feelings (annoyance, anxiety, helplessness, lack of interest in other things, sense of control, fatigue and anger) in the participants during the stay-at-home order (e.g., "Compared with before the pandemic, your feelings of being annoyed during the stay-athome order have…"). A 5-point Likert-type scale was used: 1 = significantly reduced, 2 = slightly reduced, 3 = basically unchanged, 4 = slightly aggravated and 5 = severely aggravated. Demographic variables included gender, age, body mass index (BMI) and occupation (including undergraduate students, graduate students and employed people). The control variables were demographic variables, including gender, age, body mass index (BMI) and education level. *p < .05. **p < .01. ***p < .001. categorical variables (daytime napping and occupation) were coded as dummy variables, and taking daytime naps as before (original code of 2) and undergraduate student (original code of 1) were coded as 0. A bilateral α < 0.05 was considered statistically significant. In terms of lifestyle, compared with before the pandemic, 37% of the participants reported that their exercise levels were slightly worse, 43.2% of the participants reported that their learning/working efficiency was slightly worse and approximately half (50.2%) of the participants reported that time using electronic devices increased significantly during the stay-at-home order. In terms of negative emotions, only anxiety and annoyance were slightly aggravated, accounting for 46.8% and 53.1%, respectively. In terms of sleep quality, 51.7% of the participants reported that sleep quality remained unchanged during the stay-at-home order compared with before the pandemic (see Table 2 ). A partial correlation analysis was performed to preliminarily examine the relationships between sleep pattern changes, daytime napping, lifestyle and negative emotions. The partial correlation analysis results between the major variables after controlling the demographic Before the pandemic Stay at home Sleep latency(min) variables are shown in Table 3 . Changes in lifestyle were significantly correlated with differences in wake-up times, falling asleep times, sleep latency and sleep quality before and after the pandemic, and were not significantly correlated with differences in sleep duration. Negative emotions were not significantly correlated with differences in wake-up times on weekends and sleep duration on weekdays, and significantly correlated with changes in other sleep patterns. Daytime napping was significantly associated with lifestyle and negative emotions. These results provided preliminary support for further analysis. To explore changes in the sleep patterns of the participants before and after the pandemic, wake-up time, time falling asleep, sleep duration and sleep latency were used as dependent variables to perform a 2 (pandemic: before the pandemic, stay at home) × 2 (weeks: F sleep latency (3,926) = 3.78, p < .05 (see Table 5 ). In detail, in the group with no daytime napping and less daytime napping than before, compared to before the pandemic outbreak, the wake-up and after the pandemic were significant on weekdays, but were not significant on the weekends (see Table 6 ). In the group of no daytime napping, the differences in wake-up time and sleep duration between before and after the pandemic were significant on the weekdays, but on weekends, only the difference in sleep latency between before and after the pandemic was significant. In the group taking more daytime naps, there were significant differences in wake-up time, time falling asleep, sleep duration and sleep latency between before and after the pandemic on weekdays, and significant difference in wake-up time between before and after the pandemic on weekends. In the group with less daytime napping, there were significant differences in wake-up time, time falling asleep and sleep duration between before and after the pandemic on weekdays. Although sleep patterns became later on the weekdays during stay-at-home orders in all groups, the group taking daytime naps as before had minimal variation. There were no significant differences in sleep quality between before and after the pandemic in each group. A delayed sleep-wake pattern, increased sleep duration and sleep latency had significant impacts on lifestyles and emotions (the specific results are presented in Table 7 and Table 8 ). Change in sleep quality was one of the important factors affecting lifestyle and negative emotions. Specifically, greater sleep quality during stay-athome orders positively predicted exercise level (β = 0.18, p < .001) and learning/working efficiency (β = 0.28, p < .001), and negatively TA B L E 5 Simple effect test of the interaction between the pandemic and daytime napping Regarding changes in daytime napping, learning/working efficiency in the group taking more daytime naps was significantly lower than that in the group taking daytime naps as before (β = −0.10, p < .01), and electronic device use in the groups taking more daytime naps and taking fewer daytime naps was significantly greater than in the group taking daytime naps as before (β taking more daytime naps = 0.17, p < .001; β taking less daytime naps = 0.10, p < .01). Negative emotions in the group that reported taking more daytime naps were significantly higher than in the group that reported taking daytime naps as before (β annoyance = 0.12, p < .001; β anxiety = 0.12, p < .001; β helplessness = 0.10, p < .01; β uninterested = 0.11, p < .001; β losing control = 0.13, p < .001; β fatigue = 0.16, p < .001; β anger = 0.10, p < .01), and negative emotions in the group that reported taking fewer daytime naps were significantly higher than those in the group that reported taking daytime naps as before (β annoyance = 0.16, p < .001; β anxiety = 0.17, p < .001; β helplessness = 0.14, p < .001; β losing control = 0.11, p < .001; β fatigue = 0.11, p < .01; β anger = 0.14, p < .001). Annoyance and anxiety in the group that reported no daytime napping were higher than in the group that reported taking daytime naps as before (β annoyance = 0.08, p < .05; β anxiety = 0.08, p < .05). As a public health emergency of international concern, COVID-19 caused individuals to experience acute psychological stress, and af- Studies have shown that increased digital media usage near bedtime and decreased physical activity occurred during the COVID-19 pandemic (Cellini et al., 2020; Ong et al., in press ). In line with this research, the present study demonstrated that acute stress as a result of the pandemic affected not only individual lifestyles (increased use of electronic devices, decreased exercise levels and low learning/working efficiency), but also affected individual psychological well-being (increased levels of anxiety and annoyance) during the stay-at-home orders. It has been shown that the SARS pandemic, which was similar to the COVID-19 pandemic, affected people's mental health and led to negative emotions, such as fear, loneliness and annoyance (Tam et al., 2004; Yu et al., 2005) . proposed that the pandemic would aggravate negative emotions, such as anxiety, depression and panic (Xiang et al., 2020) . attention should be paid to people's mental health under the stress of a pandemic. Since the outbreak of COVID-19, a series of studies have focused on individuals' sleep changes during the pandemic (Cellini et al., 2020; Léger et al., 2020; Sanford et al., 2014) . One study found that among 1,005 adults, 54% reported that their sleep worsened during the period of lockdown (Léger et al., 2020) . Another study investigating 1,310 young adults showed that sleep rhythms were significantly delayed, with increased sleep duration and lower sleep quality (Cellini et al., 2020) . Investigators also proposed that acute stress responses triggered by the pandemic promoted the secretion of stress-related neuropeptides and hormones, thereby promoting wakefulness and affecting sleep architecture (Sanford et al., 2014 ). In the current study, we found that the sleep rhythms of young adults were delayed, sleep duration was increased and sleep latency was prolonged during the pandemic. Generally, a late sleep-wake schedule is linked with poor mental and physical health (Dong et al., 2019; Roenneberg et al., 2012) . We further investigated the influence of the changes in sleep-wake schedules on individual lifestyles and negative TA B L E 7 Results of hierarchical regression analysis of the changes in sleep patterns, daytime napping and lifestyles between before and after the epidemic (Haraden et al., 2017; Kayaba et al., 2020; Krističević et al., 2018; Morita et al., 2015) . Delayed sleep-wake patterns can negatively predict positive emotions and social experiences (Asaoka et al., 2004; Segura-Jiménez et al., 2015; Totterdell et al., 1994) . During the pandemic, time of falling asleep and wake-up time were later than before the pandemic, which may also cause people to feel stronger negative emotions and suffer from unsatisfactory lifestyles, such as low working/learning efficiency. Besides the adverse effects of delayed sleep phases, the consequences of poor sleep quality also require attention. In the present study, up to 26.67% of participants reported that their sleep worsened (slightly or substantially) between before and after the pandemic. Our results revealed that poor sleep quality could also positively predict the participants' negative emotions and electronic device use, but negatively predict their exercise levels during the stay-at-home orders. Studies have demonstrated that compared to sleep quantity, sleep quality is closely related to health, mood, life satisfaction, tension and exhaustion (Pilcher et al., 1997 In addition to the benefits of nocturnal sleep, appropriate daytime napping can improve individuals' mood, alertness and performance (Brooks & Lack, 2006; Jones, 2009; Tietzel & Lack, 2001) . These improvements are found to be significant in habitual daytime nappers but not non-nappers (Evans et al., 1977; Milner et al., 2006) . Our results testified that taking regular daytime naps during the stay-at-home order also had the same advantages, and appropriate daytime napping can reduce negative emotions caused by pandemic-induced acute stress. Furthermore, maintaining regular daytime naps as they were before the pandemic effectively reduces negative emotions, enhances learning (working) efficiency and decreases electronic device use Research also indicated that the ability to fall asleep during daytime, sleep quality and benefits accrued from napping may be responsible for the frequency of an individual choosing to take a nap (Milner & Cote, 2009 This study has the following limitations. First, because the COVID-19 pandemic is an emergency, the researchers could not precisely collect information before the pandemic. Therefore, this study utilized personal recollection to collect information regarding behaviours and emotions before the pandemic, which to some extent achieves the purpose of exploring differences between before and after the pandemic. However, the bias in memory still exists and the cross-sectional nature of this study cannot accurately reflect the causal relationship between the variables. Second, in the selection of participants, this study only focused on young adults with stable physical and mental health and did not explore the psychological and behavioural impacts of the COVID-19 pandemic on people of other ages (such as adolescents, middle-aged adults and older adults) during the stay-at-home order, which could be a research area for future studies. Finally, this study preliminarily explored changes in sleep patterns, lifestyle and psychological well-being during the stay-at-home order and revealed the stabilizing effect of regular daytime napping on sleep patterns, lifestyle and psychological well-being, and provided information regarding maintaining psychological health and sleep health during the pandemic. However, it should be noted that unhealthy lifestyles and negative emotions could also affect sleep adversely. The European Academy for Cognitive Behavioral Therapy for Insomnia (CBT-I Academy) explored individuals' changes in sleep during COVID-19 stay-at-home orders and proposed that reductions in duration of exposure to sunshine and exercise levels, and negative psychological status are the main factors that affect sleep health (Altena et al., 2020) . Another study also suggested that changes in social zeitgebers (such as regular work schedules, social activities and living environments) greatly disrupted individuals' sleep patterns during the pandemic (Cellini et al., 2020) . Future clinical studies and interventions may consider the bidirectional relationship of sleep problems, individual lifestyle and emotions. Our study found that the stay-at-home orders delayed the sleepwake phase, prolonged sleep duration and sleep latency, changed lifestyles and aggravated negative emotions among young adults during the COVID-19 pandemic. Delayed sleep after the pandemic outbreak affected lifestyles and negative emotions. The current study has some noteworthy findings regarding regular daytime napping being an effective way to stabilize sleep patterns and biological rhythms, maintain good habits, alleviate the effect of acute psychological stress and prevent and control mental disorders during the pandemic. No conflicts of interest declared. DW and ZJ: data collection, data analysis, and writing and revision of the manuscript. LG and ZB: data analysis and editing the manuscript. MN: conceptualization, funding acquisition, methodology, supervision and review and editing of the manuscript. Research Foundation, China (No. 2019A1515012182). The data that support the findings of this study are available from the corresponding author upon reasonable request. 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