青森保健医療福祉研究4（1）; 22-31: 2022

Original article

https://doi.org/10.24552/00002195 ©青森県立保健大学

Link between social jet lag caused by“weekend catch-up sleep”, sleep debt,
subjective symptoms, and lifestyle habits
1）

2）

Terumi Kogawa and Mitsuko Iwabuchi

1 ）Aomori University of Health and Welfare
2 ）Iwate Medical University
ABSTRACT［Objective］In recent years, an increasing number of children have been complaining of physical problems as a consequence of spending after-school time at home on television, games. However, the way
children spend their time after school, their sleep habits, and their physical symptoms have not yet beenclarified. In the present study, we aimed to determine health education measures that could help maintain
good sleeping habits and improve physical and mental health by examining the association between sleep
status and subjective symptoms in middle school students.
［Methods］A survey was conducted using a self-administered questionnaire, which was filled out by the
middle school students themselves, with seeking their parents for help as necessary. The study subjects
consisted of 1,013 students who agreed to participate in the study and had no missing values. We analyzed the relationship between how middle school students spend time after school until the next day,sleep debt, social jet lag（SJL）, and subjective symptoms.
［Results］There was a difference between boys and girls in the time spent after school, with boys spending more time playing games and girls spending more time doing homework. Many girls had sleep debt
and SJL. Subjective symptoms were associated with sleep debt in both boys and girls. Gaming and homework influenced SJL in both boys and girls. Sleep debt was associated with subjective symptoms evenafter adjusting for the time spent after school until the next day.
［Conclusions］The different ways in which time was spent at home after school suggested an association
with sleeping habits. It also suggested a relationship between sleep and subjective symptoms. Therefore,
as health education for middle school students, it is necessary to convey that the way of spending timeafter school until the next day, including sleep habits, is related to subjective symptoms.

《 Key Words》 sleep debt, social jet lag, physical and mental symptoms, gaming, homework

Background and Aims
Sleep is a habit and natural act necessary forsurvival. It is intricately involved in ensuring theappropriate functioning of the nervous, immune,and endocrine systems. Sleep is vital for the maintenance and promotion of health. Above all, it isparticularly important for the growth and development of the brain during puberty; in fact, problems
Corresponding author Terumi Kogawa（E-mail: t_kogawa@auhw.ac.jp）
Aomori University of Health and Welfare
58-1 Mase, Hamadate, Aomori, Japan
Tel: 017-765-2053 Fax: 017-765-2053（Recieved January 12, 2022; Accepted May 2, 2022）22with learning motivation, academic ability, and1～4）
truancy by lack of sleep
are known to be asso5～7）
ciated with obesity . Although sleep is importantin adolescents, sleep duration reportedly reduces
8,9）with an increase in age . Children who sleep laterat night on a regular basis resolve the lack of sleep
on weekends. Consequently, the phenomenon of“weekend catch-up sleep” has recently been receiv10～12）
ing increasing attention.
The phenomenon of weekend catch-up sleep
occurs as a result of the differences in bedtimes
13,14）
between weekdays and weekend. Bedtime shift
is the difference between weekend and school day
bedtimes. Wake-up time shift is the difference
between weekend and school day wake-up times.

Link between social jet lag and subjective symptoms

Sleeping until late on weekend to eliminate weekday sleep deprivation causes sleep time shifts,
resulting in social jet lag（SJL）. Following a shortsleep time on weekdays, if the wake-up time isdelayed on weekends in the absence of any social
restrictions, the phase of the circadian rhythm
causes a time difference from the sleep time zone
on weekdays. SJL is a condition in which a malfunction in sleep occurs due to phase mismatch15）
between social clock and the biological clock .
Although no studies have assessed these problems in children as a direct cause of lifestylerelated diseases, a few studies have examined theassociation of the phenomenon of weekend catchup sleep with the physical symptoms and psycho10,16）
logical state of children. Furthermore, we havethe problem of sleep debt to contend with. Sleep
debt is a condition that occurs when one does not
get sufficient sleep for days and the debt adds up
17,18）
from days to weeks. While weekend catch-up
sleep eliminates sleep debt and lowers the risk for
19）
16,20～22）
hypertension , many studies
have pointed
out the negative effects of weekend catch-up sleep
and sleep debt. In contrast, the lifestyle behaviorsof children are significantly associated with psychosomatic symptoms, suggesting that inappropriate
lifestyle behaviors are likely to increase physical11）
and psychological health risks . The association
between lifestyle and sleeping habits in children
also needs to be assessed, and health education
should consider all the habits involved in daily living. In the present study, we aimed to determine
health education measures that could help maintain
good sleeping habits and improve physical andmental health by examining the association
between sleep status and subjective symptoms in
middle school students.

Methods
Study design
This was a cross-sectional study, conducted inTown A（population: approximately 20,000）, locatedin the northern part of Honshu, the main island ofJapan. Since 2006, after the merger of towns andvillages, Town A has been conducting lifestylerelated disease prevention medical examinations
at four middle schools in the town. This study
requested a lifestyle-related survey at the above
time of the medical examination.
Survey method
The participants of the study were 1,047 students who were enrolled in the third year of middle school between 2008 and 2012. The survey

used a self-administered questionnaire, which was
filled out by the middle school students themselves, with seeking their parents for help as necessary. The study subjects consisted of 1,013 students who agreed to participate in the study andhad no missing values.
Survey items
Sleep duration was calculated based on the difference between bedtimes and wake-up times on
weekdays and weekends. Weekend catch-up sleep
was calculated as SJL based on the difference
15）
between weekday and weekend sleep duration .
In addition, sleep debt was calculated as the difference between bedtimes on weekends and week23）days . Subjective symptoms of unknown causes
are usually classified as general malaises experi12）
enced by adolescents . The main symptoms inchildren include headache, abdominal pain, poor
early rising, fatigue, and so on, and children with
two or more symptoms have been reported to24）
range about 20～30％ . With reference to these,the questionnaire of subjective symptoms wasassessed by each item（fatigue, difficulty concentrating, and irritability; shoulder stiffness, headache,and abdominal pain; and sleepiness during class,difficulty waking up, and trends in insomnia）.
These symptoms were assessed over the previous
month on a four-point scale（0: never; 1: rarely［about 1～3 days a month］; 2: occasionally［about
1～3 days a week］; 3: always［more than 4 days aweek］）.
In addition, participants were asked how theyspent their time after school until the next day
when they went to school（hereafter, after school）,
including information on extracurricular activities,
television and other media use, gaming, homework,
dinner, and breakfast. During the survey period,
SNS was not yet common; therefore, other media
included watching DVDs and using personal computers. Information on breakfast skipping was also
gathered, as breakfast is related to sleep, andschool students who miss breakfast are reported to25）
be sleep deprived .
Statistical analyses
Data from 1,013 participants having no missing
values were analyzed. The time spent in different
activities was estimated in minutes. Mann-Whitney
U test was initially used for comparisons between
boys and girls. Correlations between subjective
symptoms and how time was spent after school
were assessed using Spearman’s correlation coefficient. Correlations between the time spent after23

青森保健医療福祉研究4（1）; 22-31: 2022

school and SJL were assessed using the partial
regression coefficient. The relationships between
the time spent after school and SJL and sleep debt
were evaluated using multiple regression analysis.
Further, a polytomous logistic regression analysis
was conducted after adjusting for degree of obesity, breakfast, dinner, extracurricular activities,
television or any other media use, gaming, andhomework. The contexts for each symptom leveland sleep debt and SJL were compared that withreference to 0 levels. All statistical tests were twosided. Statistical analysis was performed using
SPSS software, version 25.0, for Windows（SPSS
Japan, Tokyo, Japan）.

significantly less time playing games than boys
（p＜.001）, but they spent significantly more timeon breakfast（p＝.028）and homework（p＜.001）.
Moreover, boys’ weekday sleep duration was significantly longer than that of girls（p＜.001）; however,weekend sleep duration, sleep debt, and SJL weresignificantly greater among girls（p＜.001）.
Table 2 presents the relationship between each
symptom level, how time was spent after school,and sleep debt and SJL among boys and girls. No
correlations were found between any of the symptoms and time spent after school having dinner orparticipating in extracurricular activities or obesity
for boys, or between the symptoms and televisionor any other media use for girls. Gaming was more
often associated with symptoms among boys thanamong girls. Sleep debt was correlated with symptoms（fatigue, irritability, abdominal pain, difficulty
waking up, and trends in insomnia）in both boys
and girls.

Ethical considerations
Participants were provided with written andverbal explanations concerning the purpose of thestudy, their right to withdraw their participation,
assurance of their anonymity, and publication of theresults. Written and verbal explanation was provided to their parents/guardians too, on the school
visit day. The participants and their parents/
guardians provided written informed consent toparticipate in the study. This study was approvedby the ethics committee of the Hirosaki University
Graduate School of Medicine（No. 2008-170）.

Effect of time spent after school on sleep debt andsocial jet lag
Table 3 shows the effects of time spent after
school on sleep debt and SJL. For boys, the factors
affecting SJL were gaming and homework, with apositive relationship with gaming time and negative relationship with homework. Likewise, the factors affecting SJL for girls were gaming and homework, with a negative association with breakfast
time. No factors affecting sleep debt were found inboth boys and girls.

Results
Participant characteristics
The participants comprised 528 boys and 485
girls（Table 1）. The time spent after school in various activities differed between the sexes. Girls spent

Table 1. Gender differences in how time was spent after school
Boys

Girls

N＝528

N＝485

p-value

M

SD

M

SD

Breakfast
DinnerExtracurricular activities
Television or any other media use
GamingHomework

12.7
22.4
137.1
132.7
89.6
80.4

5.7
8.8
30.4
73.5
58.4
40.1

13.5
23.0
134.5
127.4
48.9
99.8

5.5
8.8
39.8
69.7
57.5
42.0

.028
.258
.489
.242
＜.001
＜.001

Weekday sleep duration（min.）Weekend sleep duration（min.）Sleep debt
Social jetlag

453.7
508.8
55.2
0.765

44.7
71.1
74.8
0.69

443.6
528.1
84.6
0.960

40.6
72.8
77.3
0.73

＜.001
＜.001
＜.001
＜.001

after school: the time between going home after school and the one going to schoolon the following day
M: mean, SD: standard deviation
The unit of each item was one minute.
p-values were obtained using a Mann-Whitney-U test.

24

Link between social jet lag and subjective symptoms

Table 2. Correlation between symptoms and how time was spent after school
Breakfast

DinnerExtracurricular
activities

Televisionor anyothermedia use

GamingHome
work

Degree ofobesity

Sleep debt

.016

.048

−.040

.028

.016

−.024

.112

SJL

Boys
Fatigue

＊

−.088

＊

＊＊

.135

＊

−.079

＊＊

＊＊

.114

＊＊

＊

.083

＊

.093

Difficulty concentrating

−.065

−.007

.022

.093

.001

.077

Irritability

−.064

.046

−.024

.089

.129

−.129

.021

.091

Shoulder stiffness

−.109

−.038

−.036

−.030

.003

.031

.059

.094

−.050

.01

.009

−.005

−.037

.115

.041

−.105

.038

.025

.064

−.031

−.078

.147

Headache

＊

.009

−.013

.022

−.005

.036

Abdominal pain

−.080

−.054

.017

.037

.103

Sleepiness during class

−.082

−.024

.034

.069

.079

Difficulty waking up
Trends in insomnia

−.030

.068

−.064

.042

＊

＊＊

＊

＊＊

.136

.078
＊

.008
＊＊

＊
＊

＊＊

.134

＊

.021

.052

−.002

.004

.030

−.018

.049

.093

.111

−.028

−.035

.055

.039

.025

.032

.03

.120

−.081
−.034

Girls
Fatigue＊＊＊

Difficulty concentrating

−.028

−.050

−.004

.071

.100

−.077

−.02

−.001

Irritability

−.007

−.043

.035

.070

.025

−.005

.07

.140

＊

＊＊

＊

.101

Shoulder stiffness

−.020

.098

−.046

−.011

−.003

−.046

.06

.052

.085

Headache

−.063

.027

−.010

−.038

.055

−.027

.142

.040

.040

Abdominal pain

−.009

.059

−.022

−.045

.045

−.010

−.02

.148

.111
.048

Sleepiness during class

−.079

−.042

.018

Difficulty waking up

−.093

.088

.091

Trends in insomnia

−.039

.039

−.025

＊

＊

.046

.051

−.002

.107

.014

.117

＊

＊＊

＊＊

−.099

.034

.048

＊

−.037

.024

.173

＊

.006

.058

.116

＊＊

＊＊

.140

＊＊

.075

＊＊

after school: the time between going home after school and the one going to school on the following day
Spearman’s correlation coefficient＊＊＊: p＜0.05,: p＜ 0.01

Context of each symptom level and sleep debt andsocial jet lag
The relationships between each symptom leveland sleep debt and SJL, after adjusting for how
time was spent after school, are presented inTables 4 and 5. For boys, fatigue, difficulty concentrating, irritability, shoulder stiffness, abdominal
pain, and difficulty waking up were the symptoms
associated with sleep debt after adjusting theirtime spent after school. SJL was associated with
fatigue, difficulty in concentration, shoulder stiffness, and difficulty waking up（Table 4）. In girls,
sleep debt and SJL were both associated with
fatigue, abdominal pain, and difficulty waking up（Table 5）.

Discussion
This study examined the association between
sleeping habits and subjective symptoms among
middle school students, and indicated that the timespent after school doing different activities differedby gender. Although one previous study did not
find any gender-related differences in terms of bed26）
times and wake-up times on weekdays , otherstudies have reported that girls wake up earlier on
27,28）
weekdays but later on weekends. In a previous
study, girls were found to be significantly more29）
morning oriented than boys . In another study,

girls also showed longer sleep times on weekends
30）
and were more likely to have SJL . Our study
showed that girls have more sleep debt and SJL
conditions than boys. Although one report alerts to
31）
17,18）
sleep debt in children , the majority of studies
do not report gender differences for children’s andadolescents’ sleep debt.
21,22）
Other studies, have indicated that boys who
engage in prolonged weekend catch-up sleep tocompensate for weekday sleep deprivation may
spend less time viewing television. Moreover, delayed
sleep timing during adolescence is partly driven byenvironmental factors that can displace sleep, such
32,33）
as viewing television, or any other media use.
In the present study, weekend catch-up sleep was
related to difficulty waking up among boys andgirls, and gaming appears to be a significantly
related background factor. Hence, it is necessary to
be careful about game time, which can lead tosleep debt and weekend catch-up sleep. In contrast,
as homework had a negative association with SJL
for both boys and girls, it was considered thatdoing homework at a fixed time, including on
weekends, was a favorable way to reduce SJL.
Excessive study time on weekends has been reported
34）
to cause depression ; however, setting aside regular and moderate homework time might help
improve the health of middle school students.
25

青森保健医療福祉研究4（1）; 22-31: 2022

Table 3. Relationships between time spent after school and SJL, and, sleep debt
SJL

B

SE

β

t-value

p

VIF

0.207
0.697
0.170
0.146
0.002
0.003

1.021
1.078
1.066
1.178
1.196
1.039

Boys
Breakfast
DinnerExtracurricular activities
Television or any other media use
GamingHome work−0.007 0.006 −0.059 −1.264
0.001 0.004
0.018
0.389
0.001 0.001
0.060
1.375
−0.0010−0.065 −1.455
2.00E-03 0.001
0.136
3.071
−0.002 0.001 −0.129 −2.942

Girls
Breakfast
DinnerExtracurricular activities
Television or any other media use
GamingHome work−0.015 0.007 −0.113 −2.303 0.022 1.191
0.008 0.004
0.092
1.892 0.059 1.182−0.001 0.001 −0.044 −0.981 0.327 1.016
7.21E-05
00.007
0.151 0.880 1.027
0.001 0.001
0.090
1.966 0.050 1.038−0.002 0.001 −0.096 −2.086 0.038 1.061

Sleep debt
Boys
Breakfast
DinnerExtracurricular activities
Television or any other media use
GamingHome work−0.061
0.282−0.130−0.070−0.0270.072

0.622 −0.005 −0.097 0.922 1.196
0.401
0.033
0.703 0.483 1.178
0.101 −0.057 −1.286 0.199 1.021
0.046 −0.068 −1.510 0.132 1.078
0.058 −0.021 −0.475 0.635 1.066
0.083
0.038
0.861 0.390 1.039

−1.07
0.734
0.030
0.019
−0.0090.026

0.702 −0.076 −1.525
0.436
0.083
1.68
0.087
0.016
0.342
0.051
0.017
0.373
0.062 −0.007 −0.143
0.086
0.014
0.301

Girls
Breakfast
DinnerExtracurricular activities
Television or any other media use
GamingHome work

0.128
0.094
0.732
0.710
0.887
0.763

1.191
1.182
1.016
1.027
1.038
1.061

after school: the time between going home after school and the one going to school on thefollowing day
SJL and sleep dept were evaluated multiple regression analysis
B: Partial regression coefficient, SE: Standard error, VIF: Variance Inflation Factor

Although there are no studies on sleep debt andphysical symptoms in children, sleep debt has beenreported to exacerbate colitis inflammation and35）
delay recovery in adults , and thereby being supposed to be similar in girls too. A girl’s functional
abdominal pain or irritable bowel syndrome is associated with vagal activity, which is closely associ36）
ated with sleep . It is necessary to pay attention
to the symptoms peculiar to girls from childhood.
Based on the above earlier studies and the resultsof this study. It is therefore necessary to convey
how to spend the time after school as the content
of health education that helps maintain good sleep
habits and improves physical and mental health ofmiddle school students.
A limitation of this study was that, as a cross26

sectional study, we could not directly state that
inappropriate sleeping habits worsened the experienced symptoms. Additionally, the study area waslimited to a town, it is necessary to be careful togeneralize our findings. Nonetheless, we also focusedon other information, such as subjective symptoms
associated with sleeping habits after school. we
focused on other information related to sleeping
habits after school. Further studies are needed toassess and validate these findings in greater detail.

Conclusions
In the present study, we observed a relationshipbetween sleep habits and certain physical andmental symptoms in Japanese middle school students. The different ways in which time was spentLink between social jet lag and subjective symptoms

Table 4. Context of each symptom level and sleep debt and, SJL（boys）
Symptom

Level

n

（％）

Sleep debt

SJL

exp

p

95％ CI

expp

95％ CI

1
1.000
1.001
1.004

0.908
0.725
0.049

0.997-1.003
0.997-1.004
1.000-1.008

1
1.325
1.136
1.974

0.089
0.481
0.003

0.958-1.832
0.796-1.622
1.269-3.070

1
1.001
0.997
1.008

0.309
0.165
0.003

0.999-1.004
0.993-1.001
1.003-1.014

1
1.158
0.860
2.145

0.325
0.483
0.014

0.864-1.551
0.565-1.310
1.170-3.933

1
1.001
1.005
0.995

0.577
0.003
0.110

0.998-1.004
1.002-1.009
0.988-1.001

1
1.137
1.410
1.013

0.408
0.099
0.965

0.838-1.544
0.938-2.120
0.557-1.844

1
1.002
1.005
0.999

0.285
0.030
0.741

0.998-1.005
1.000-1.009
0.992-1.005

1
0.933
1.527
1.782

0.739
0.080
0.050

0.620-1.404
0.951-2.453
1.001-3.175

1
1.000
0.999
1.003

0.973
0.679
0.664

0.997-1.003
0.992-1.005
0.999-1.016

1
1.028
0.672
0.529

0.864
0.324
0.617

0.746-1.417
0.305-1.48
0.044-6.419

1
1.001
1.006
1.010

0.283
0.033
0.060

0.999-1.004
1.000-1.012
1.000-1.021

1
1.081
1.278
0.766

0.598
0.473
0.765

0.81 -1.443
0.654-2.499
0.133-4.412

1
1.000
1.000
1.002

0.890
0.819
0.282

0.997-1.003
0.997-1.004
0.998-1.007

1
1.203
1.054
1.285

0.232
0.778
0.299

0.888-1.628
0.729-1.524
0.801-2.064

1
1.001
1.002
1.007

0.539
0.224
0.001

0.998-1.004
0.999-1.006
1.003-1.010

1
0.878
1.239
1.710

0.464
0.255
0.006

0.62 -1.244
0.857-1.792
1.169-2.5

1
1.001
1.001
1.004

0.397
0.735
0.181

0.998-1.005
0.995-1.007
0.998-1.011

1
1.217
1.734
1.853

0.319
0.070
0.093

0.827-1.791
0.957-3.141
0.903-3.804

Fatigue
0355 （67.2）
1
126 （23.9）
237 （ 7.0）
3
10 （ 1.9）
Difficulty concentrating
0281 （53.2）
1160 （30.3）
2
69 （13.1）
3
18 （ 3.4）
Irritability0317 （60.0）
1133 （25.3）
2
54 （10.2）
324 （ 4.5）
Shoulder stiffness
0407 （77.1）
1
67 （12.7）
234 （ 6.4）
3
20 （ 3.8）
Headache0405 （76.7）
1102 （19.3）
2
17 （ 3.2）
3
4 （ 0.8）
Abdominal pain0370 （70.1）
1
137 （25.9）
217 （ 3.2）
3   4 （ 0.8）
Sleepiness during class0229 （41.5）
1
174 （33.0）
2
94 （17.8）
341 （ 7.7）
Difficulty waking up
0
262 （49.6）
1118 （22.4）
2
83 （15.7）
3
65 （12.3）
Trends in insomnia
0433 （82.0）
1
64 （12.1）
2
18 （ 3.4）
3
13 （ 2.5）

Exp: exposure, p: p value, 95％ CI: 95％ confidence interval
A polytomous logistic regression analysis was conducted after adjusting for degree of obesity, breakfast, dinner, extracurricular activities, television or any other media use, gaming, and homework.
Compared with the 0 level group27

青森保健医療福祉研究4（1）; 22-31: 2022

Table 5. Context of each symptom level and sleep debt and, SJL（girls）
Symptom

Level

n

（％）

Sleep debt

SJL

exp

p

95％ CI

expp

95％ CI

1
1.003
1.002
1.006

0.058
0.249
0.003

1.000-1.006
0.999-1.005
1.002-1.010

1
1.144
1.123
1.542

0.416
0.510
0.046

0.828-1.581
0.795-1.588
1.007-2.360

1
1.000
1.000
0.997

0.837
0.876
0.524

0.997-1.002
0.997-1.004
0.988-1.006

1
0.927
1.19
0.953

0.596
0.388
0.912

0.702-1.225
0.802-1.768
0.403-2.249

1
1.002
1.004
1.005

0.106
0.013
0.064

1.000-1.005
1.001-1.008
1.000-1.010

1
1.26
1.433
1.512

0.121
0.054
0.138

0.941-1.688
0.994-2.066
0.876-2.611

1
1.002
1.001
1.001

0.279
0.639
0.765

0.999-1.005
0.997-1.005
0.997-1.005

1
1.261
1.148
1.338

0.185
0.505
0.168

0.895-1.776
0.765-1.721
0.885-2.023

1
1.000
0.999
1.005

0.930
0.595
0.195

0.997-1.003
0.994-1.003
0.998-1.012

1
0.951
1.282
1.325

0.748
0.284
0.487

0.699-1.294
0.814-2.020
0.600-2.925

1
1.000
1.005
1.010

0.792
0.018
0.004

0.998-1.003
1.001-1.009
1.003-1.017

1
1.045
1.411
2.373

0.772
0.133
0.022

0.774-1.412
0.900-2.213
1.135-4.960

1
1.002
1.001
1.003

0.183
0.618
0.151

0.999-1.005
0.998-1.004
0.999-1.008

1
1.165
1.063
1.495

0.323
0.729
0.093

0.861-1.575
0.753-1.501
0.935-2.390

1
1.002
1.001
1.005

0.239
0.509
0.001

0.999-1.005
0.998-1.005
1.002-1.009

1
1.181
1.208
1.594

0.343
0.319
0.008

0.837-1.667
0.833-1.752
1.130-2.247

1
1.002
1.003
1.002

0.296
0.169
0.564

0.999-1.005
0.999-1.008
0.995-1.009

1
1.367
1.328
0.834

0.062
0.271
0.681

0.984-1.898
0.801-2.202
0.35 -1.984

Fatigue0307 （63.3）
1
107 （22.0）
2
61 （12.6）
3
10 （ 2.1）
Difficulty concentrating
0259 （53.4）
1
163 （33.6）
2
53 （10.9）310 （ 2.1）
Irritability0
238 （49.1）
1
149 （30.7）
2
74 （15.3）
3
24 （ 4.9）
Shoulder stiffness
0305 （62.9）
1
78 （16.1）
2
54 （11.1）
3
48 （ 9.9）
Headache0331 （68.2）
1
109 （22.5）
235 （ 7.2）
3
10 （ 2.1）
Abdominal pain0318 （65.6）
1117 （24.1）
2
39 （ 8.0）
311 （ 2.3）
Sleepiness during class0
179 （36.9）
1163 （33.7）
2105 （21.6）
3
38 （ 7.8）
Difficulty waking up
0
222 （45.8）
1
98 （20.2）
2
76 （15.7）
3
89 （18.3）
Trends in insomnia
0362 （74.6）
1
83 （17.1）
2
28 （ 5.8）
312 （ 2.5）

Exp: exposure, p: p value, 95％ CI: 95％ confidence interval
A polytomous logistic regression analysis was conducted after adjusting for degree of obesity, breakfast, dinner, extracurricular activities, television or any other media use, gaming, and homework.
Compared with the 0 level group28

Link between social jet lag and subjective symptoms

after school suggested an association with sleeping
habits. It also suggested a relationship between
sleep and subjective symptoms. Thus, maintaining
good sleeping habits during adolescence is essential
for improving mental and physical health. The content of health education should cover not only
sleeping habits but also homework and gaming
tendencies.

Acknowledgments
This work was supported by JSPS KAKENHI
Grant Numbers JP18592406, JP 21592845.

Conflict of Interest Statement
The authors declare that they have no conflict ofinterest.

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Link between social jet lag and subjective symptoms

原著論文「週末の寝だめ」によって引き起こされる社会的時差ぼけと
睡眠負債，自覚症状と生活習慣との関連
1）

2）

古川照美 ，岩渕光子
1）青森県立保健大学
2）岩手医科大学（2022年 1 月12日受付：2022年 5 月 2 日受理）

抄録〔目的〕 近年，放課後の時間をテレビ，ゲームなどに費やした結果として，身体的な問題を訴える子供たちが増えている。しかし，放課後の過ごし方や睡眠習慣，身体的症状について明らかになっているとは言い難い。本研究では中学生の睡眠状態と自覚症状との関連を検討することにより，良好な睡眠習慣と心身の健康の維持，向上のための健康教育対策に示唆を得ることを目的とした。
〔方法〕 調査は，中学生本人が必要に応じて保護者に協力を求めながら記入する自記式質問紙で行った。本
研究への参加に同意し，欠損値のない1,013人を最終的な解析対象とした。中学生の放課後から翌日までの過ごし方，睡眠負債，社会的時差ぼけ（SJL），自覚症状との関係を分析した。
〔結果〕 放課後の過ごし方は男子と女子で差があり，男子はゲームに，女子は宿題に多くの時間を費やしていた。多くの女子が睡眠負債と SJL を持っていた。自覚症状は，男子と女子の両方で睡眠負債と関連していた。ゲームと宿題は，男子と女子の両方で SJL に影響を与えていた。睡眠負債は，放課後から翌日までの過ごし方の時間を調整した後でも自覚症状と関連していた。
〔結論〕 放課後から翌日の過ごし方の違いと，睡眠習慣との関連が示唆された。また，睡眠と自覚症状との関連も示唆された。したがって，中学生に対する健康教育として，睡眠習慣を含む，放課後から翌日までの過ごし方が自覚症状と関連していることを伝える必要がある。
Aomori J. Health Welfare, 4（1）; 22-31: 2022
Key words: 睡眠負債，社会的時差ぼけ，自覚症状，ゲーム，宿題
連絡先古川照美（E-mail: t_kogawa@auhw.ac.jp）
青森県立保健大学
青森市大字浜館字間瀬58-1
Tel: 017-765-2053 Fax: 017-765-2053

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