1. Aerobic exercise improves subjective sleep quality through multiple mechanisms
Tatyana N Pashibin
19 November 2015
Marquette University

2. Introduction
Sleep is a major component to health, mental functioning, and body regulation. Sleep
disturbances and poor sleep quality have correlated to impairments in daily functioning as well
as increased risk of morbidity such as obesity, hypertension, and anxiety [4]. Sleep and exercise
are thought to be closely related, as those who have poor sleep quality typically do not want to
exercise and those who exercise regularly tend to have better sleep quality [1, 3]. Exercise is
known to decrease the risk of developing many of the diseases that poor sleep quality can
contribute to, and exercise is also assumed to affect sleep quality. Therefore exercise may
contribute to disease prevention both through direct physiological mechanisms as well as through
indirect mechanisms such as improving sleep quality. Exercise is a well-accepted non-
pharmacological intervention to alleviate sleep difficulties and insomnia, but the research
investigating the direct influence of exercise on sleep is in the early stages [1].
Subjective sleep quality (SSQ) is commonly used to assess sleep habits and sleep quality
through questionnaires and sleep logs. These tools may not be completely accurate but they are
reliable in identifying potential sleeping problems and generating a basic understanding of sleep
habits and quality. Does moderate-intensity aerobic exercise improve subjective sleep quality? If
so, what are the possible mechanisms? This paper will discuss barriers to studying the effects of
exercise on sleep, summarize what the available literature states about subjective sleep quality in
relation to aerobic exercise, and provide future directions for research.
Rationale for studies included
The studies included in this paper generally focus on SSQ as measured with the Pittsburg
Sleep Quality Index (PSQI) [2] while subjects continue to be community-dwelling. The PSQI

3. measures 7 components of sleep health, and a total score of 5 or greater is considered poor
reported sleep quality. The studies were selected based on populations who could benefit from
better sleep quality, their applicability to varying populations based on accessibility of study
intervention, and the public health recommendation to exercise regularly at a moderate-intensity.
Most studies focused on extended exercise training programs opposed to acute effects to observe
the effects of an active lifestyle.
Barriers to studying exercise and sleep quality
Many factors contribute to sleep quality including cardiovascular diseases, lifestyle
choices, light exposure, stress, substance abuse, and mental health [4, 9]. Often times in sleep
research healthy individuals are used as subjects to minimize the effects of these variables. While
using healthy subjects can help to control for contributing factors it also generally creates a
ceiling effect, as healthy individuals tend to have better sleep quality and less potential for
improvement [1, 5]. Poor sleep quality can be a contributor to the aforementioned variables so it
becomes difficult to distinguish whether poor sleep quality is a cause or a result of disease and
lifestyle [3]. Research conducted in sleep laboratories over an extended period can better control
these variables but the costs of running such projects is high and typically focus on aspects
unrelated to exercise and sleep [7]. The most practical way to conduct human research on sleep
quality is to use at-home polysomnography and tools to assess SSQ. These methods do not alter
subject lifestyle and also give a more accurate representation of how exercise will affect sleep
quality in an applicable setting.
Psychology, exercise, and sleep

4. Better mental health and mood are thought to improve sleep quality, and exercise
positively effects mood and psychological well-being [4, 9]. Gerber et al hypothesized that a
perceived lack of physical activity and lower physical fitness would correlate to lower sleep
quality independent of actual exercise in students in their 20’s. Perceived lack of exercise and
self-rated poor fitness both correlated to a higher prevalence of sleep disturbances. The main
point of the study was that perhaps the sleep-promoting effects of exercise were less dependent
on actual exercise and more dependent on beliefs surrounding physical activity levels and fitness
[5]. Those who perceived lack of fitness may not feel as healthy and thus may have more
depressive symptoms which would likely decrease their sleep quality.
Several studies have investigated the effect of exercise on mood and sleep. These studies
have controlled for mood and depressive variables during analysis to find if exercise has an
isolated effect on sleep. Reid et al reported improvements in quality of life, depressive
symptoms, and sleep quality after a 16 week moderate-intensity exercise program in combination
with sleep-hygiene education class in older adults. The controls in the study attended sleep-
hygiene education and attention-matched activities. The effects of exercise were isolated from
mood in analysis and found to improve PSQI scores significantly in the exercise group [9].
Gebhart et al conducted a similar study and found comparable results, but the study did not
collect data for mood and was unable to control for this factor during analysis. The results are
shown below [4].

5. Potential contributors to enhanced mood with exercise are due to outside factors such as
light exposure, increase in endorphins, and the social aspect of group exercise classes [6, 8].
These variables can be assessed subjectively through questionnaires and objectively through
blood sampling. Next, this review will explore how objective measures align with subjective
measures of sleep quality.
SSQ compares to objective measures of sleep
King et al state that exposure to sunlight during at-home exercise sessions could have
been a confounding variable as light has a positive impact on sleep quality and mood [6]. Sun
exposure has influences on hormone secretion including melatonin from the pineal gland.
Melatonin is secreted at night and is sleep-inducing [8]. Lee at al investigated whether it is
sunlight exposure during physical activity or the activity itself that causes increases in melatonin
and better SSQ. The researchers used PSQI and blood draws to assess melatonin, cortisol, and
norepinephrine levels. The results are summarized in the table below [8].
Gebhart et alReid et al

6. EG1= Sun exposure, EG2= Exercise, EG3= Sun exposure and exercise, EG4= control, no sun or exercise.
The exercise condition showed less improvement in SSQ and hormone secretion than the two
conditions with light. This suggests that light exposure has a greater influence than exercise does
on hormone secretion impacting sleep. What is further interesting is that the exercise and sun
exposure group had the shortest sleep duration but the best PSQI scores. This suggests that sleep
quality due to hormone improvements is more important than sleep duration for SSQ.
The most comprehensive way to study sleep is through polysomnography. Slow-wave
sleep can be measured by polysomnography. Slow-wave sleep is considered higher quality sleep
and to be more restorative to the body [1, 3, 6]. Older adults engaging in an aerobic exercise
program for 12 months had significantly improved PSQI scores as well as longer sleep duration
and more time spent in slow-wave sleep compared to their baseline measures and the controlled
condition [6]. This suggests that SSQ and polysomnography are closely related and typically
reflective of each other, and this allows subjective sleep quality to be used as a general indication
of subjective sleep quality.

7. Conclusion
The research determining and understanding a direct mechanism for the influence of
aerobic exercise on sleep quality is in the early stages. The data available so far is promising that
aerobic exercise has a positive effect on sleep, but more studies need to be conducted and control
for contributing factors of exercise on sleep quality. Conducting research in a sleep laboratory
where lighting, diet, and other factors can be better controlled will help to reveal the direct effect
of aerobic exercise on sleep. However, contributing factors such as mood and changes in fitness
will likely interfere if studying chronic exercise in a laboratory, and these factors are hard to
control. The effects of exercise that indirectly influence sleep quality include improved mood,
disease status, and light exposure. These factors can improve total wellness and thus help to
promote sleep, and this indicates that regular aerobic exercise at a moderate-intensity can help
improve sleep quality and health. Better sleep quality and regular physical activity both improve
health and reduce the risk of many of the same diseases, but both have significant impacts on
each other. Therefore, regular exercise and healthy sleep are important factors in maintaining
good fitness and high quality of life.

8. Works Cited
1. Atkinson G., Davenne D. Relationships between sleep, physical activity and human health.
Physiol Behav 90: 229–235, 2009.
2. Buysse DJ, Reynolds CF, Monk TH, Berman SR, Kupfer DJ. The Pittsburg sleep quality
index: a new instrument for psychiatric practice and research. Psychiatry Res 28: 193-213, 1989.
3. Driver HS, Taylor SR. Sleep and exercise. Sleep Med Rev 4: 387–402, 2000.
4. Gebhart C, Erlacher D, and Schredl M. Moderate exercise plus sleep education improves self-
reported sleep quality, daytime mood, and vitality in adults with chronic sleep complaints: a
waiting list-controlled trial. Sleep Disord 2011: published online 2011.
5. Gerber M, Brand S, Holsboer-Trachsler E, Puhse U. Fitness and exercise as correlates of sleep
complaints: is it all in our minds? Med Sci Sports Exerc 42: 893-901, 2010.
6. King AC, Pruitt LA, Woo S, Castro CM, Ahn DK, Vitiello MV, Woodward SH, Bliwise DL.
Effects of moderate-intensity exercise on polysomnographic and subjective sleep quality in older
adults with mild to moderate sleep complaints. J Gerontol 63: 997-1004, 2007.
7. King AC, Oman RF, Brassington GS, Bliwise DL, Haskell WL. Moderate-intensity exercise
and self-rated quality of sleep in older adults: a randomized controlled trial. JAMA. 277: 32-37,
1997.
8. Lee H, Kim S, Kim D. Effects of exercise with or without light exposure on sleep quality and
hormone responses. J Exerc Nutr Biochem 18: 293-299, 2014.
9. Reid KJ, Baron KG, Lu B, Naylor E, Wolfe L, Zee PC. Aerobic exercise improves self-
reported sleep and quality of life in older adults with insomnia. Sleep Med 11: 934-940, 2010.
10. Sherrill DL, Kotchou K, Quan SF. Association of physical activity and human sleep
disorders. Arch Intern Med.158: 1894-1898, 1998.

9. Study Subjects Methods Results Aerobic exercise
improved
subjective sleep
quality?
Gebhart et al 114 men and
women with
sleep
complaints but
no other
disorders
Not randomly
selected to 6 week
exercise+sleep
hygiene or just sleep
hygiene class,
exercise 1x weekly
with group instruction
and at home twice
weekly of comparable
intensity. Subjects
completed
questionnaires (PSQI,
mood, and quality of
life) at baseline, post,
and 3 –month follow-
up (follow-up only
for exercise group)
Both groups saw
improvements in
PSQI over 16
week period, but
more pronounced
in exercise group
(-3.1). Exercise
group also
improved from
baseline to
follow-up.
Exercise group
improved sleep
quality, sleep
latency, sleep
duration,
efficiency,
psychological
condition and
quality of life.
Perhaps- the
effects of the
sleep hygiene
course were not
controlled for in
the intervention
group, which
were not
randomly
selected for their
group. However,
improvements
across
measurements
were apparent in
the intervention
group.
Gerber et al 862 students
average age 25
Subjects filled out
various
questionnaires about
their physical
activity, perceived
physical fitness, and
perceived sleep
quality.
Those who
perceived better
physical fitness
and reported
doing more
physical activity
also perceived
themselves to
have better
physical fitness,
though physical
fitness and
reported levels of
physical were
only moderately
correlated.
N/A- aerobic
physical activity
wasn’t
distinguished
from physical
activity in
general, and
actual physical
activity was
probably not
reflected in self-
reported physical
activity. Authors
suggest that
beliefs of good
physical fitness
are more
important in
influencing self-
reported sleep
quality.

10. King,
Bliwise et al
Adults 55 and
older who were
sedentary but
healthy with
moderate sleep
complaints.
Randomly selected to
intervention or
control group.
Exercise group
attended group fitness
classes 2x weekly for
45 minutes and 3
days on their own for
12 months. Control
group was offered 90
minute health
education 1x weekly
for 12 months.
Polysomnography,
gxt and
questionnaires
assessed at baseline, 6
months, and 12
months.
PSQI and diaries
showed improved
SSQ significantly
better than
controls at 12
months.
Exercisers had
greater duration
of sleep and
SWS, which is
associated with
better sleep
quality.
Yes- it appears
that chronic
exercise
improves
subjective and
objective sleep
quality.
Authors mention
potential
interaction of
light during
home-based
exercise sessions.
King,
Haskell et al
43 older adults,
Age 50-76
years,
No CVD or
stroke,
Sedentary,
moderate sleep
complaints but
not diagnosed
with sleep
disorder.
Randomly selected
participants for wait-
list control group or
for 16 week
moderate-intensity
exercise program two
days in class format
for 60 minutes and 2
at home for 40
minutes. PSQI and
sleep diaries were
collected at baseline,
8 weeks, and 16
weeks. Gxt at
baseline and 16
weeks.
Exercise group
had a significant
decrease in PSQI
score (3.3 point
decrease),
reported sleep
duration
increased by an
hour in exercise
subjects,
Yes
Lee et al 40 healthy men
in their 20’s
who stayed
indoors for most
of the day.
4 experiments: 30
minutes sun exposure
outside; exercise 5x a
week for 30 minutes
at 50-60% HRR; both
exercise and sun
exposure; neither.
Subjects did each
protocol for one
week, then had a one
week wash-out period
Sun exposure
group: slept 7.75
hours, PSQI was
4.91, 20 minutes
to sleep,
melatonin change
12.8.
Exercise group:
24 minutes to fall
asleep, 7.45
hours to fall
No- exercise with
sun exposure and
sun exposure
group had better
improvements in
PSQI and
hormone levels
than exercise
alone and control
group.
Exercise only

11. before the next
protocol. PSQI and
blood draws were
used to assess sleep
and melatonin and
cortisol levels,
respectively.
asleep, PSQI
5.76, melatonin
change 11.19.
Exercise with sun
exposure: 16
minutes to fall
asleep, 7.13
hours of sleep,
PSQI 4.66
melatonin change
14.55.
Control: 28
minutes to fall
asleep, 7.13
hours of sleep,
PSQI 7.97,
melatonin change
9.45.
significantly
improved
subjective sleep
quality with
sunlight
exposure.
Reid et al 23 community
dwelling
healthy older
adults over 55
years old with
difficulty falling
or staying
asleep and had
daytime
impairment.
Randomly selected to
aerobic physical
activity group or non-
physical activity
group for 16 weeks.
Assessed subjective
sleep quality, mood
and quality of life at
baseline and post
intervention.
Assessed activity and
sleep with Actiware
at baseline and post.
PSQI scores
significantly
decreased for the
exercise group
but not the
control.
Depressive
symptoms and
quality of life
also improved in
the exercise
group but not the
controls.
Yes- significant
improvement in
PSQI scores even
when controlling
for improvement
in depressive
symptoms.
Sherrill et al 722 healthy
adults 40 and
over
Surveyed participants
about daily physical
activity and sleep
quality/disturbances.
Separated into groups
of sleep disturbances
and physical activity
and ran statistical
analyses.
People who
walked more than
6 blocks per day
at an average
pace, who did
regular physical
activity at least
once a week, and
participated
regularly in
exercise
programs had
less difficulty
To some extent.
Regular physical
activity and
weekend
vigorous physical
activity were
seen to improve
self-reported
sleep quality in
the overall study
population but
this trend was not
observed in

12. initiating and
maintaining sleep
(DIMS).
However, women
who reported
engaging in
regular physical
activity and
vigorous activity
on the weekends
were at higher
risk of having
DIMS.
women who
participated in
regular activity
and vigorous
weekend activity.