Associations between chronotype and physical activity and well-being in adults

ABSTRACT

Circadian rhythms influence a preference for people’s time of activity and sleep time during the day and the hours of best performance. The aim of the study was to assess the associations between chronotype, physical activity, and well-being in adults aged 20–50. The chronotype, physical activity and well-being scores were determined based on the Composite Scale of Morningness (CSM) questionnaire, the International Physical Activity Questionnaire (IPAQ) and the Well-Being Index (WHO-5) questionnaire, respectively. Study data consisted of the answers of 213 respondents (including 64 men) who took part in an online survey. The Spearman rank correlation coefficient and the matrix scatter plots were used to check the correlations between the CSM score and quality of life parameters’ values. General linear models (GLMs) were performed to find differences in quality-of-life parameters between different combinations of sex and chronotype. Morning types showed the highest value of well-being score (mean = 13.48) while evening types the lowest one (mean = 8.35). Evening types spent the most time sitting compared to other chronotypes. Results of this study revealed the significant effect of chronotype on well-being and physical activity among adults. These findings suggest that chronotype is an important factor that psychologists and personal trainers should take into account.

KEYWORDS:

• Chronobiology
• circadian rhythm
• CSM
• E-types
• eveningness
• morningness
• M-types
• sedentary behavior

Introduction

Circadian rhythmicity in humans is represented by a complex phenotype derived from numerous genetic factors determining the chronotype. The human population is characterized by inter-individual variability regarding the rhythmic timing of the body’s functions. Depending on the internal circadian rhythm, people differ in their preferred duration of sleep and activity, which can be expressed as a type of chronotype (Adan et al. 2012). Chronotype is a biological construct that refers to the entire system, specifically its organization, taking into account the relationships of individual oscillators to each other. Protein differences in the components of the biological clock resulting from inter-individual genetic differences make individuals differently synchronized with the light and dark cycle (Roenneberg et al. 2019). In addition, the chronotype depends on both age and sex, and it can be disturbed, for example, by social schedules resulting from the organization of work or study time (Roenneberg et al. 2007). To determine the chronotype, various questionnaires verifying time preferences for activity and sleep are used, called “morningness-eveningness” (ME) (Horne and Östberg 1976).

There are three chronotypes: Morning-types (M-types), Evening-types (E-types), and Neither-types (N-types). Within the M-type and E-type chronotypes, extreme and moderate types can also be distinguished. People without clear circadian preferences are classified as N-types, because they show intermediate features (Montaruli et al. 2021). This chronotype dominates, constituting about 60% of the adult population, with the remaining 40% classified as M-type or E-type (Adan et al. 2012; Montaruli et al. 2017).

M-types and E-types show clear differences in terms of sleep and wake times, as well as psychophysical activity during the day. M-types wake up early and go to bed early, while peak performance is reached early in the day (Taillard et al. 2004). E-types similarly perform these activities later and reach the peak of both cognitive and physical performance in the second half of the day (Adan et al. 2012; Montaruli et al. 2021). One of the main factors that influence these differences is the variability of the melatonin profile, which is the main predictor of sleep onset (Mongrain et al. 2004). In adults, the E-type chronotype is more susceptible to diseases, shows less physical activity, and is characterized by shorter sleep and social jet lag (Martínez-Lozano et al. 2020). Increasingly, research shows that physical activity is considered another factor regulating the circadian rhythm (Manfredini et al. 1998). Thomas et al. (2020) indicate that evening chronotypes may benefit from phase acceleration induced by morning or evening exercise. For morning chronotypes, evening exercise may have a negative effect of exacerbating circadian misalignment. Individuals with the evening chronotype also show a greater amount of time spent sitting compared to the morning type (Plekhanova et al. 2023; Sempere-Rubio et al. 2022). Given this, chronotype-based personalization of exercise time could help mitigate circadian mismatch in young adults. Vitale and Weydahl (2017) indicate that the available research in the literature still does not provide comprehensive answers on the impact of chronotype on physical activity.

Research also shows a correlation between the chronotype and the adopted attitudes or personality traits. M-types are classified as more conscientious, agreeable, and ambitious, while E-types tend to be more extroverted, neurotic, and emotionally unstable (Hill and Chtourou 2020; Zajenkowski et al. 2019). Moreover, there is a correlation between the chronotype, the state of mood, and physical performance at certain times of the day (Hill and Chtourou 2020). Jankowski (2015b) points out that there is a significant and complex correlation between chronotype and well-being, which is still poorly understood. Analysis by Li et al. (2023) revealed that shift workers with evening chronotypes have worse mental health than those with other chronotypes. These authors indicate that chronotype is an unrecognized factor affecting mental health in the workplace.

People with the evening chronotype reach the peak of their physical performance and good mood much later. For example, the study examining the performance of 75 adolescent soccer players in three tests of agility, aerobic endurance and explosive power revealed that morning-type individuals scored better in the morning tests (at 9 a.m.), whereas the evening ones achieved better scores in evening tests (at 6 p.m.). No effect was observed for neither types (Roveda et al. 2020). Therefore, imposing working or studying hours on them in opposition to their chronotype can result in a worsening of their mood and a lack of desire or energy to engage in physical activity. Consequently, evening types will spend more time in a sedentary position, which in turn may also exacerbate bad mood (Facer-Childs et al. 2018; Martínez-Lozano et al. 2020).

In this study, we aimed to assess the associations between chronotype, physical activity and well-being in adults. We expected evening people to be less physically active, to spend more time sitting, and to have worse well-being due to the mismatch between their internal circadian rhythm and social activity timeframes such as work, school, so-called “social jetlag” (Wittmann et al. 2006).

Materials and methods

Responses to an online survey of 213 adults (including 64 men) aged 20 to 50 were evaluated in the present study. The data was acquired using the snowball sampling method and the survey was placed on a Facebook group dealing with the promotion of surveys. Students of various faculties and non-students in various professions and degrees of education participated in the study. In addition to basic open and closed questions, the survey included Polish versions of the Composite Scale of Morningness (CSM) (Jankowski 2015a), the International Physical Activity Questionnaire (IPAQ) (Biernat et al. 2007), and the Well-Being Index (WHO-5) (Topp et al. 2015). The results obtained from the CSM questionnaire made it possible to classify the respondents into three chronotypes, including M-types, E-types, and N-types (Shahid et al. 2012). In this study, the term “chronotype” was used for “individualized sleep time preferences based on genetics, development, and external influences,” according to the existing definition (Kontrymowicz-Ogińska 2011). This is the first study linking physical activity and well-being with chronotype. It is an introduction to further research on scheduling the day. Potentially, research on chronotype and various activities can result in higher work efficiency, more activity and better well-being.

The CSM questionnaire refers to various aspects of functioning during the day, such as: wake rhythm, physical and intellectual performance, and arousal. People are asked to choose their preferred time of day from the given clock hours or to compare with other people in the population. For each question, it was possible to obtain from 1 to 4 or 5 points (in 3 questions), with a total between 13 and 55 points. Depending on the number of points, the respondents were classified in the following way: a score of 22 or below indicates an evening type (E-type), 23 to 44 neither type (N-type) and above 44 a morning type (M-type; Jankowski 2015a; Smith et al. 1989).

The results obtained from the IPAQ questionnaire informed the level of weekly physical activity expressed in MET units – min/week (Metabolic Equivalent of Work). The answers from the questionnaire were converted by calculating the product of the coefficient for a given activity with the number of minutes and days of its performance. The results from all types of activities were added together. Time spent sitting – utilized in previous studies as a measure of physical activity – was also extracted from the answers.

The level of well-being was determined by summing the scores for each of the five questions in the WHO-5 questionnaire. For each question, it was possible to obtain from 0 to 5 points (the higher the number, the better the well-being), with score totals ranging between 0 and 25 points. If the score totaled less than 13, the authors suggested further testing for depression.

Research was conducted in accordance with the Declaration of Helsinki. The consent of the Ethical Committee of the Wroclaw University of Environmental and Life Sciences No. 17/2023 was obtained.

Statistical methods

Descriptive data of men and women, including sex and chronotype, were assembled in contingency tables, compiled by age, the sum of CSM questionnaire points, well-being, and physical activity scores, using basic statistical measures (mean, standard deviation, range). A Mann-Whitney U test was applied to compare the total point values of the CSM questionnaire between men and women on scores for well-being, physical activity, and time spent sitting. To check the correlation between CSM points, well-being scores, physical activity, and time spent sitting, scatterplots were used. Next, a Spearman rank correlation coefficient was applied. Subsequently, the general linear models (GLMs) were performed to examine the impact of chronotype and sex on life quality parameters controlling age (as a covariate) of participants.

Results

Descriptive statistics

Most participants represented the Neither type (N-type) of chronotype when considering the sample collectively and separately for men and women. In the case of male and female participants, the E-types predominated over the M-types. There was a trend for all participants to have about twice as many E-types as M-types, but the difference did not reach statistical significance (Table 1). This means that the difference was due to the characteristics of the selected sample however, this result cannot be extrapolated to the general population.

Table 1. Descriptive statistics of the study sample. Mean±SD or n (column %).

Variable	Men (n = 64)	Women (n = 149)	All (N = 213)
Age	24.9 ± 4.5	24.5 ± 6.3	24.6 ± 5.8
Studying/working students students + odd jobs workers part-time workers full-time	16 (25.0) 24 (37.5) 2 (3.1) 22 (34.4)	44 (29.5) 66 (44.3) 7 (4.7) 32 (21.5)	60 (28.2) 90 (42.3) 9 (4.2) 54 (25.4)
Level of education primary vocational secondary higher	1 (1.6) 3 (4.7) 35 (54.7) 25 (39.1)	0 (0.0) 2 (1.3) 95 (63.8) 52 (34.9)	1 (0.5) 5 (2.3) 130 (61.0) 77 (36.2)
Chronotype M-type N-type E-type	7 (10.9) 46 (71.9) 11 (17.2)	16 (10.7) 101 (67.8) 32 (21.5)	23 (10.8) 147 (69.0) 43 (20.2)
CSM score	33.3 ± 7.6	32.4 ± 7.6	32.7 ± 7.6
Well-being score	11.7 ± 4.6	10.0 ± 4.8	10.5 ± 4.8
Physical activity score	4595.5 ± 4590.1	2352.9 ± 2703.7	3057.7 ± 3553.6
Time spend on sitting (min.)	400.4 ± 197.3	383.5 ± 192.3	388.7 ± 193.4

The mean age of participants was 24.6 years old (±5.8 years; range: 20–50 years), with most participants aged 21 years. Descriptive statistics for the CSM questionnaire scores and life quality parameters are shown in Table 1.

Men and women CSM and life quality parameters scores

Male and female participants did not differ in CSM scores. Males’ scores were, on average, two points greater than females, but this difference did not reach a level of statistical significance. Two out of three life quality characteristics revealed differences between males and females. Well-being and physical activity scores were significantly higher in the case of male subjects (Table 2).

Table 2. CSM and life quality parameters scores comparison between men and women.

Variable	Women			Men			Mann-Whitney test value
	n	R	Me±Q	n	R	Me±Q	Z	p
CSM score	149	104.6	32 ± 6	64	112.6	34 ± 5	−0.87	0.3867
Well-being score (points)	149	100.4	10 ± 3	64	122.4	12.5 ± 3.5	−2.38	0.0172
Physical activity score (points)	120	79.1	1629 ± 1134.13	55	107.5	3093 ± 2694.75	−3.44	<0.001
Timespent sitting (minutes)	119	85.1	360 ± 150	53	89.8	360 ± 100	−0.57	0.5673

R – mean rank, Me – median value, Q – quartile deviation.

CSM vs. life quality of men and women

The intercorrelations of CSM score and life quality parameters are demonstrated using scatter plots (Figures 1 and 2). CSM score was positively correlated with well-being scores and negatively related to time spent sitting (Table 3). This means that M-type participants, both men and women, had better well-being scores (Figure 1) and spent less time sitting (Figure 2). Well-being was also correlated with physical activity and time spent sitting – the greater the physical activity scores, the better their well-being; the more time spent sitting, the worse their well-being. Additionally, the more time spent sitting, the lower their physical activity score (Table 3).

Figure 1. Scatter plot of CSM score and well-being score for men and women.

Figure 2. Scatter plot of CSM score and time spent sitting for men and women.

Table 3. Spearman rank correlation coefficients (r_s) between CSM points, physical activity, well-being and time spent sitting for all participants.

Variables	CSM score	Well-being score	Physical activity score
Well-being score	0.29*
Physical activity score	0.15	0.24*
Time spent sitting (min.)	−0.18*	−0.29*	−0.17*

In the case of female subjects, CSM score was also positively correlated with well-being (r_s = 0.33, p < 0.001) with M-type females scoring better. For male participants, there were no significant correlations between CSM and life-quality parameters – the time spent sitting achieved a p-value close to borderline significance (r_s = −0.27, p = 0.055). The only significant association found in men was a reverse correlation between time spent sitting and well-being (r_s = −0.34, p = 0.01). For women the similar relation was observed (r_s = −0.3, p < 0.001). For women, an additional significant correlation was the positive correlation between well-being and physical activity (r_s = 0.29, p = 0.001). The lack of significant correlations in men, compared to women, may occur due to a biased sex ratio (149 women vs. 64 men) in our sample.

Life quality vs. chronotype and sex controlling for age

Three separate general linear models (GLMs) were built for well-being, physical activity and time spent sitting as dependent variables (Table 4). Two predictors: sex and chronotype, revealed the significant impact on the well-being score of the participants controlling age. The well-being score for men was significantly greater than for women (11.66 vs. 10.04), using a post-hoc Tukey test (HSD for unequal numbers: p = 0.0449). Moreover, evening types had significantly lower well-being scores than morning types (8.35 vs. 13.48; p < 0.001) and neither types (8.35 vs. 10.7; p = 0.0442) but there was no significant difference between M-types and N-types (13.48 vs. 10.7; p = 0.0969). To sum up, M-types had the greatest well-being scores and E-types the worsts. This trend was the same for both male and female individuals (Figure 3). In the second model only sex had a significant influeance on physical activity score controlling age of the participants. Men had a higher score of physical activity than women (4595.5 vs. 2352.9) at a statistically significant level using Tukey test (HSD for unequal numbers: p < 0.001). In the last model only chronotype showed a significant effect on time spent sitting controlling age. E-types had the longest time spent sitting (473,4 minutes) and M-types the shortest one (343,7 minutes). Tukey post-hoc test revealed a borderline significance for the difference between E-types and N-types (HSD for unequal numbers: p ~0.05). Of all chronotype categories, E-types spent the most time sitting, and the trend was the same for both sexes (Figure 4).

Figure 3. Chronotype category and sum of well-being (mean ± 95% CI).

Figure 4. Chronotype category and time spent sitting (mean ± 95% CI).

Table 4. GLM model of life quality parameters (dependent variables, three separate models) in sex and chronotype categories (predictors in each model) controlling age as a covariate.

# model	df1, df2	F	p
1. Well-being score (points)
intercept	1. 208	54.11	<0.001
chronotype	2. 208	8.59	<0.001
sex	1. 208	4.91	0.0278
age	1. 208	0.01	ns
adjusted R-squared of the model	R^2Adj. = 0.09
2. Physical activity score (points)
intercept	1. 170	12.8	<0.001
chronotype	2. 170	1.52	ns
sex	1. 170	16.17	<0.001
age	1. 170	0.33	ns
adjusted R-squared of the model	R^2Adj. = 0.08
3. Time spent sitting (minutes)
intercept	1. 167	30.39	<0.001
chronotype	2. 167	4.73	0.01
sex	1. 167	0.63	ns
age	1. 167	0.14	ns
adjusted R-squared of the model	R^2Adj. = 0.03

ns – non significant (p > 0.05).

Discussion

In this study the relationships between chronotype and well-being and time spent sitting were found significant – the more evening type the less well-being score and more time spent sitting. These results might be important for various aspects of life i.e. mental health or physical activity level.

The distribution of chronotypes we obtained differed slightly from the results of other authors. It is estimated that the ratio of type E to type M should be approximately 1:1 (Fabbian et al. 2016). In our study, however, the number of E-types was almost twice as large as M-types. This condition was most likely caused by a surplus of younger people (the mean age of the respondents = 24.6), who have been more frequently found to be E-type (Mecacci et al. 1986; Zawilska et al. 2008).

The results obtained in this study revealed sex differences in quality-of-life parameters. Men showed significantly higher activity (p < 0.001) and well-being (p = 0,0449). These conclusions are consistent with Siwiński and Rasińska’s (2015) results. Talaei et al. (2013) also showed, based on studies of an Iranian population, that men have significantly higher levels of physical activity than women. Bergier et al. (2014) confirmed this relationship. The sample of this study might be biased for sex due to the overrepresentation of women. This fact should be taken into account, when considering differences in observed relationships in men and women.

Achieved CSM values were positively correlated with well-being scores and time spent sitting. It follows that M-type respondents had better well-being scores and spent less time sitting. Au and Reece’s (2017) meta-analysis found a weak association between E-type chronotypes and depressive symptoms. Of the 36 existing studies these authors reviewed, only one found no association. It described people with a clinically diagnosed SAD (Seasonal affective disorder). Hidalgo et al. (2009) suggested that clinical trials may rather demonstrate that E-type chronotypes be a premorbid feature preceding depressive symptoms. Gulec et al. (2013) found that people demonstrating evening chronotype features were more prone to developing psychological symptoms compared to people with a morning preference. In our study, M-types were characterized by the highest value of well-being (mean = 13.48) and E-types the lowest one (mean = 8.35). E-types had significantly lower well-being scores than M-types (p < 0.001) and N-types (p = 0.0442). This trend was the same for both male and female individuals. Also, a study including over 29 thousands of teenagers aged 10–18 years indicated that evening chronotypes tended to have lower emotional well-being, which suggest that the relationship observed in our study occurs not only in adults but also in childs and adolescents (Gariépy et al. 2019). It could mean that this phenomenon is common in E-types individuals regardless of their age.

Another important study examined how the shift towards summertime affects the well-being of students. Summertime hours were used as an experimental manipulation to see, if they shifted student subjects towards the M-type, yet no significant changes in mood or life satisfaction were observed. The small to moderate correlations in both studies suggest significant and poorly understood complexity in the correlation between well-being and circadian activity type (Jankowski 2015b). They also suggest the need to better understand and investigate the mechanisms underlying this correlation (Bullock 2019).

A systematic review by Sempere-Rubio et al. (2022) showed that chronotypes are clearly related to physical activity levels and time spent sitting. Specifically, they concluded that E-types spent more time sitting than M-types, an association that was also found in the present study. We found that E-types spent the most time sitting, compared to both other chronotypes.

A study of the daily number of steps in relation to the chronotype showed that the more individuals tend toward the M-type, the more daily steps they take (Allee et al. 2020). Sempere-Rubio et al. (2022) likewise confirmed that M-type is associated with greater physical activity. A study of German students (Krueger et al. 2023) showed that morning chronotype was also associated with a higher visceral fat mass and the relationship was particularly dependent on physical activity. The same study also showed that morning-type participants tended to have greater skeletal muscle mass, than evening-type subjects. While the present study found no direct correlation between chronotype and physical activity, an indirect impact has been noted. The level of physical activity had a proportional impact on well-being: less activity in the form of a lot of time spent sitting was associated with worse well-being, which directly affected the chronotype.

The timing of physical activity may also be important. In a study by Lang et al. (2022), participants were classified into two groups, one exercising in the morning and the other in the evening. The morning exercise group showed a significantly advanced (earlier) circadian phase (27.5 ± 32.0 min) while sitting delayed it (−34.3 ± 53.2 min). It has also been shown that morning exercise led to more sleepiness in the evening.

Conclusions

The present study confirmed the correlation of chronotype with well-being and time spent sitting – the more morning their chronotype, the better their mood and the less time they spent sitting. There was no direct correlation found between chronotype and physical activity, but an indirect effect was shown between well-being and time spent sitting. A higher physical activity score was associated with greater well-being, and the more time spent sitting, the lower the well-being was found to be.

While E-types spent significantly more time sitting than other chronotypes, we concluded that further research is needed on the associations between chronotype and physical activity and the other factors that may influence them. Results of this study prove how important factor chronotype is. The impact of chronotypes should be taken into account in the studies of physical activity and well-being. First of all, this effect should be considered by personal trainers when planning the time of physical activity for their charges. Moreover, psychologists may use these findings in individual therapies to achieve their better results. We suggest that the introduction of flexible working hours by employers, scheduling physical activity and study hours will allow people of different chronotypes to work and learn more effectively with better well-being. Further research on this relationship and its mechanism is needed.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors