Elsevier

Physiology & Behavior

Volume 247, 1 April 2022, 113705
Physiology & Behavior

Original article
The CLOCK 3111T/C polymorphism is associated with hour-by-hour physical activity levels only on weekends among Japanese male and female university students

https://doi.org/10.1016/j.physbeh.2022.113705Get rights and content

Highlight

  • CLOCK 3111T/C polymorphism is associated with sleep-wake rhythms including activity.

  • No study has examined CLOCK 3111T/C or physical activity (PA) for an entire week.

  • PA among genetically evening-oriented students was low only on Saturday.

  • PA among genetically evening-oriented students was low only on Saturday.

  • Social obligations may mask the genetically determined biological rhythm of PA on weekdays.

Abstract

Background

: CLOCK 3111T/C has been shown to be closely associated with morningness-eveningness, such as sleep-wake rhythms in healthy humans. However, previous studies examined the physical activity (PA) in a single day, and no study has investigated the relationships between CLOCK 3111T/C polymorphism and PA for an entire week. It was hypothesized that the CLOCK 3111T/C polymorphism might be associated with diurnal PA patterns, especially on the weekends.

Methods

: Eighty-one university students (male, n = 14; female, n = 67; age, 20.4 ± 2.9 years) wore a digital accelerometer for 7 successive days, including the weekend, to collect hour-by-hour objectively-measured PA. CLOCK 3111T/C polymorphism was assessed using the oral mucosa. During the study, participants recorded their wake time and bedtime each day. Furthermore, lifestyle-related variables (i.e. morningness–eveningness, habitual meal and sleep timings) were collected using questionnaires. Linear mixed-effects models assessed the association of polymorphism (TT carriers vs. TC+CC carriers) with wake time and bedtime as well as daily PA throughout the week (time).

Results

: TT carriers had an earlier wake time (weekly mean: 44 min [95% CI, −82 to −5 min], time interaction: p = 0.026) and bedtime (weekly mean: 30 min [95% CI, −61 min to − 15 s], time interaction: p = 0.048) than TC+CC carriers. Furthermore, TT carriers’ wake time and bedtime on Saturday were significantly later than on other days (gene interaction: all p < 0.05). On Saturday, the hour-by-hour PA in TT carriers was significantly greater than that in TC+CC carriers (hourly mean 1.7 min [95% CI, 0.2 to 3.4 min], time: p < 0.001, group: p = 0.028, interaction: p = 0.155).

Conclusions

: CLOCK 3111T/C polymorphism may be associated with objectively measured hour-by-hour PA only on Saturday. Academic/social obligations may mask the genetically determined biological rhythm of PA on weekdays.

Introduction

Ensuring an appropriate level of physical activity (PA) is essential for maintaining health in young individuals, as physical inactivity is a factor that contributes to at least 35 unhealthy conditions, including cardiorespiratory and immune dysfunction [1]. Unfortunately, few young individuals perform sufficient PA to realize any benefits. Although the World Health Organization recommends that children and adolescents participate in a minimum of 60 min of moderate to vigorous PA each day [2], the PA levels among youth remain low worldwide [3]. For instance, the average daily step counts among Japanese in their 20 s (males, 7913; females, 6772) were much lower than the government targets for individuals in this age group (males, 9000; females, 8500) [4]. Effective approaches to increase PA levels in young individuals are thus still warranted.

Circadian rhythms in mammals are coordinated by an endogenous circadian clock located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus [5]. Based on the idea that the circadian timing system has a strong influence on diurnal preference (i.e. morningness–eveningness), a series of recent investigations studied the association of morningness–eveningness with circadian clock-related genes. A single-nucleotide polymorphism (SNP) in the 3′-flanking region of the CLOCK gene (311 T/C; rs1801260) was suggested to influence sleep and activity in healthy humans. Studies have reported that the rs1801260*C allele is associated with an evening preference [6,7], although negative findings have also been reported [8], [9], [10]. Based on these inconsistent results, the influence of CLOCK 3111T/C carriers on human behavior merits further investigation.

Regarding PA, evidence concerning the link between PA and CLOCK 3111T/C is very limited. A few studies have investigated the associations between PA and CLOCK 3111T/C carriers [11,12], but these studies assessed ‘total PA levels in a day’ using questionnaires. Besides PA, a previous study further found that CLOCK 3111T/C polymorphism was associated with weekly rhythms of behavior. Garaulet et al. (2011) investigated the associations between CLOCK 3111T/C polymorphism and dietary habits among overweight/obese adults [13]. They found that breakfast hours among CLOCK 3111C carriers were later than those among T carriers, particularly during weekends [13]. Unfortunately, they only reported weekly total PA levels. Given that CLOCK genes may regulate diurnal rest-activity rhythms, the time of day in which PA is performed should be investigated.

To our knowledge, only two studies have found that CLOCK 3111T/C polymorphism influences the hour-by-hour diurnal rhythms of human PA. Bandin et al. (2013) reported that among middle-aged obese women, TC+CC carriers showed a delayed acrophase—which characterizes ‘evening-type’ subjects—in comparison to TT carriers, indicating reduced PA levels at 7:00–9:00 and 21:00–22:00, under free-living conditions [14]. Similarly, Benedetti et al. (2008) investigated diurnal PA levels among depressed patients in laboratory-based experiments [15]. They found that the hour-by-hour PA levels among CLOCK 3111C carriers were higher only in the second half of the day (from the end of lunch until lights out) and did not differ markedly in the morning [15]. These findings suggested that CLOCK 3111T/C may be associated with diurnal PA rhythms under free-living conditions.

However, one of these two studies used seven-day average PA data [14], while in the other, the sampling duration was a single day [15]. In humans, PA reflects not only biological activity-rest rhythms but also social factors and obligations, such as work or school hours. In this sense, the human activity in a given day varies, particularly between weekdays (workdays) and weekends (free days). In fact, previous studies showed that the PA levels on weekdays and weekends differed markedly among adolescents [16] and adults [17]. Because morningness and eveningness (especially eveningness) are related to the PA levels in adolescents [18] as well as adults [19], weekly PA rhythms, including sleep hours (especially on weekends), should be discussed. In the previous studies that investigated PA in a single day, morningness–eveningness, which was partly regulated by CLOCK 3111T/C polymorphisms, may have been masked by social factors. As described above, delayed breakfast hours among CLOCK 3111C carriers were more prominent on weekends than weekdays [13]. Furthermore, Randler et al. (2013) found that among adolescents (11–16 years old), social jetlag (discrepancy in a person's sleep pattern between weekdays and the weekend) was significantly associated with an increased body mass index (BMI) [20]. Based on these previous studies, comparisons between weekday and weekend behavior need to be investigated; however, such research is lacking.

Although Saturday and Sunday are both regular holidays in standard schools and offices, the diurnal rhythms on Saturdays may differ from those on Sundays. In such environments, Saturday is the first day of the weekend. Indeed, among adolescents whose bedtime changed throughout the week, the latest bedtime occurred on Friday and Saturday nights, not Sunday [21]. Traditionally, Saturday is known to be a day where one is likely to lose one's rhythms. Epidemiological studies have shown that unfavorable health events tend to occur on Saturdays (e.g. the incidence of acute myocardial infarction is increased on Saturdays) [22]. The mechanisms that underly these phenomena are unclear; however, the term ‘Saturday night palsy’ refers to focal peripheral nerve palsy as a result of nerve compression in alcohol misusers [23]. Previous studies have reported that the risks of various unhealthy behaviors, such as binge drinking [24] and hospitalization for associated traumatic brain injury [25], among young adults was more prominently increased on Saturdays than Sundays. For these reasons, behavior—including activity among young populations—on Saturdays seems to differ from that on Sundays.

Interestingly, previous studies found that not only were the objectively-measured PA levels lower on the weekend than on weekdays, the PA levels on Sunday were also significantly lower than those on Saturday in both adolescents [26] and adults [27]. Furthermore, individual differences may influence PA on Saturdays and Sundays in adults [28]. Scheers et al. (2012) found that while almost all adults become sedentary on Sunday, the difference in PA was most pronounced on Saturday, and some people (normal weight men) remained active on Saturday [28]. Therefore, morningness–eveningness and associated genetic factors (e.g. CLOCK 3111T/C polymorphisms) may be partially related to weekly PA variation, especially on weekends (Saturdays and Sundays). However, to date, no studies have focused on the associations between CLOCK 3111T/C polymorphism and the hour-by-hour PA levels for an entire week.

With this background, we hypothesized that CLOCK 3111T/C polymorphism would be associated with the weekly hour-by-hour PA rhythms on weekends, especially on Saturday. The present study therefore explored, under free-living conditions, whether or not the presence of this particular genetic CLOCK 3111T/C allele in young individuals was related to the diurnal weekly PA level. To test our hypothesis, we performed an experiment to assess the relationships between CLOCK 3111 polymorphism and diurnal PA levels using objectively-measured PA devices among young students under free-living conditions.

Section snippets

Participants and survey procedures

This cross-sectional study was based on the objectively-measured PA, which was determined using electronic accelerometers, a gene analysis, and a self-administered questionnaire survey. The study population included male and female university students (n = 215; males, n = 118; females, n = 97; age, 20.4 ± 2.9 years old) from 3 universities in Yamaguchi and Fukuoka Prefectures in Japan. Male participants were recruited from two sports-related universities, while most of the female participants

Participants (Fig. 1)

At baseline, 215 participants were enrolled in the present study; however, 70 were excluded because of missing gene samples (sampling refusal and/or insufficient sample of the oral mucosa). Thereafter, 59 were excluded due to insufficient accelerometer data (the exclusion criteria are described in Methods) or invalid questionnaire data (MEQ, wake time, bedtime or meal time values were insufficient). An additional 5 were excluded because of lack of sleep log data. The remaining 81 participants

Discussion

In the present study, we investigated the associations between CLOCK 3111T/C polymorphism and weekly hour-by-hour objectively-measured PA levels under free-living conditions. To our knowledge, this is the first publication to report the associations between CLOCK 3111T/C polymorphism and objectively measured weekly PA variations obtained from Monday to Sunday. We found that the hour-by-hour PA levels among TC+CC carriers were lower than those among TT carriers only on Saturday, after adjusting

Conclusions

In summary, our data showed that CLOCK 3111T/C polymorphism may be associated with objectively measured hour-by-hour PA only on Saturdays. However, genetic effects on wake times and bedtimes were observed throughout the week. These data suggest that to resynchronize their circadian clock system, genetically determined evening-oriented young individuals may rest on Saturdays. The CLOCK 3111T/C polymorphism may influence hour-by-hour PA levels in situations without any time restriction, such as

Funding

This study was supported by a grant-in-aid for Science Research from the Ministry of Education and Science of Japan (26750351, 16K01845) and Kao Health Foundation (2015).

Author contributions

Conceived and designed the experiments: RM HA NS. Performed the experiments: RM TH YH KO. Analyzed the data: RM HA MA NS. Wrote the paper: RM HA NS.

Declaration of Competing Interest

None.

Acknowledgments

We are grateful to all of the subjects for their cooperation.

References (43)

  • D.L. Robilliard et al.

    The 3111 Clock gene polymorphism is not associated with sleep and circadian rhythmicity in phenotypically characterized human subjects

    J. Sleep Res

    (2002)
  • M. Pedrazzoli et al.

    Lopes-Cendes I, Tufik S. Interactions of polymorphisms in different clock genes associated with circadian phenotypes in humans

    Genet. Mol. Biol

    (2010)
  • A.M. Chang et al.

    Human diurnal preference and circadian rhythmicity are not associated with the CLOCK 3111C/T gene polymorphism

    J. Biol. Rhythms

    (2011)
  • C. Galbete et al.

    Physical activity and sex modulate obesity risk linked to 3111T/C gene variant of the CLOCK gene in an elderly population: the SUN Project

    Chronobiol. Int

    (2012)
  • H-W. Yang et al.

    Daily rhythm of fractal cardiac dynamics links to weight loss resistance: interaction with CLOCK 3111T/C genetic variant

    Nutrients

    (2021)
  • M. Garaulet et al.

    Ghrelin, sleep reduction and evening preference: relationships to CLOCK 3111 T/C SNP and weight loss

    PLoS ONE

    (2011)
  • C. Bandin et al.

    Differences in circadian rhythmicity in CLOCK 3111T/C genetic variants in moderate obese women as assessed by thermometry, actimetry and body position

    Int. J. Obes. (Lond)

    (2013)
  • F. Benedetti et al.

    Clock genes beyond the clock: CLOCK genotype biases neural correlates of moral valence decision in depressed patients

    Genes Brain Behav

    (2008)
  • L. Arundell et al.

    Exploring when and how adolescents sit: cross-sectional analysis of activPAL-measured patterns of daily sitting time, bouts and breaks

    BMC Public Health

    (2019)
  • K. Pettee Gabriel et al.

    Ainsworth BE. Patterns of accelerometer-derived estimates of inactivity in middle-age women

    Med. Sci. Sports Exerc

    (2012)
  • R. Urban et al.

    Morningness-eveningness, chronotypes and health-impairing behaviors in adolescents

    Chronobiol. Int

    (2011)
  • View full text