1 | INTRODUCTION
Although the prevalence of asthma has started to plateau and even
decline in adolescents in Western countries,1 asthma
remains one of the most common chronic pediatric diseases with a
significant impact on quality of life (QoL).2 One of
the ways that asthma affects quality of life is through its impact on
sleep, including more frequent nighttime awakenings due to night asthma
attacks and sleep-disordered breathing.3-7 Nocturnal
asthma is a common complication, with ≥90% of the episodes of dyspnea
in asthmatics occurring at night.8 These nocturnal
asthma symptoms typically occur between 04:00 and 06:00
h.8 The most studied causes and contributing factors
to asthma exacerbations at night include night-time physiological
changes (e.g., accidental coughing, wheezing, and breathing
difficulties),6,7,9 and circadian changes in
ventilation, airway responsiveness and inflammation, mucociliary
clearance, ventilatory responses to hypercapnia and hypoxia, and hormone
levels.6 Eventually, nocturnal symptoms trigger
awakening during sleep, which impairs daily activities, increases
morbidity, induces psychometric changes, reduces QoL and these changes
can even contribute to suicidality.10 However, the
association between sleep duration and asthma is conflicting. Some
studies have found that children with asthma have generally shorter
sleep durations than do those without asthma,11 while
other studies have not found such differences in
adolescents.12 Another report found that sleep
duration in asthmatics is significantly longer than it is in
non-asthmatics.13 Recently, compared with 7–8 h of
sleep per night in adolescents, both short sleep duration (sleeping for
<7 h) and long sleep duration (sleeping for ≥9 h) had 1.22
(95% CI 1.07, 1.40) and 1.31 (1.06, 1.63) times higher OR of asthma,
respectively.7
Weekend catch-up sleep (WCUS) is defined as sleep time during the
weekend that exceeds sleep time on weekdays.5,14 WCUS
is not only an indicator of insufficient weekday sleep, but also a
compensatory phenomenon for weekday sleep debt.5,14Adolescents tend to sleep for shorter durations during the night and
exhibit a delayed sleep phase than do children.15Adolescents also tend to sleep less than children do during school days
because of the pressure of school work. In order to compensate for
insufficient weekday sleep over the entire week, adolescents then tend
to sleep more on the weekends.9,15 The effects of WCUS
on one’s overall health are conflicting. Some studies have found that
WCUS is associated with a lower risk of
hypertension,14 obesity prevention in
adults,16 and lower frequency of asthma in
adolescents.5 In contrast, WCUS had adverse effects on
executive functions,17 and contributes to suicidal
attempts and self-injury in children and
adolescents.18 Sleep disturbances in asthma are well
known. However, to the best of our knowledge, no prior studies have
addressed the influence that WCUS has on suicidal ideation in
adolescents with asthma. Current suicidal ideation is considered one of
the most important clinical predictors of future attempts and death by
suicide.19 Therefore, it is crucial to identify the
sleep factors that are associated with suicidal ideation in adolescents
with asthma in order to reduce suicide in this group.
Given this background, we hypothesized that adolescents with asthma are
more likely to have shorter total and weekday sleep duration than are
peers without asthma. We also suspected that adolescents with asthma
would have longer weekend sleep duration and longer WCUS to compensate
for their school day sleep deprivation than would adolescents without
asthma. This study had two aims. First, we investigated and compared the
differences in the clinical characteristics, sleep pattern, and mental
health status in adolescents with and without asthma. Second, we
identified the associated sleep factors for suicidal ideation in
adolescents with asthma. This second step was the main purpose of this
study. Therefore, this study was conducted to investigate the
association between sleep duration and WCUS with suicidal ideation in
adolescents with asthma in a nationally representative Korean dataset.