3 pages writing
Major Article
Napping in College Students and Its Relationship With Nighttime Sleep
Lichuan Ye, PhD, RN; Stacy Hutton Johnson, MS/MBA, RN, NE-BC; Kathleen Keane, MS, RN; Michael Manasia, BSN, RN; Matt Gregas, PhD
Abstract. Objective: To examine the habit of napping and its relationship with nighttime sleep in college students. Participants: Four hundred and forty undergraduate students who responded to an anonymous online survey in April 2010. Methods: Three questions were asked to determine the frequency, length, and timing of napping during the past month. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI). Results: The PSQI score significantly differed among self- reported nap-frequency (p D .047) and nap-length (p D .017) groups, with those who napped more than 3 times per week and those who napped more than 2 hours having the poorest sleep quality. Students who napped between 6 and 9 PM had shorter sleep on school nights compared with students in other nap-timing groups (p D .002). Conclusions: College students who are self- reported frequent, long, and late nappers may have a higher risk of poor nighttime sleep quality and more severe sleep deprivation.
Keywords: academic performance, college students, napping, sleep deprivation, sleep habits, sleep quality
A dequate sleep is integral to the well-being of indi-viduals, and it is of critical importance to adoles-cents and young adults. Insufficient and irregular sleep has been well documented among college students.
1
Poor sleep quality in college students, particularly caused
by self-imposed sleep deprivation and irregular sleep
schedules, can lead to significant emotional imbalance,
fatigue, poor concentration, impaired memory, and gener-
ally lower life satisfaction. 2–6
In fact, sleep disturbance has
been consistently rated as a top impediment to academic
performance in college students. 7–9
College students are known to voluntarily restrict their
sleep, and their flexible schedules may permit more day-
time napping. 10
Although napping is not a well-understood
sleep practice, with cultural norms differing dramatically,
napping has been suggested to be a common way for col-
lege students to cope with insufficient sleep and daytime
sleepiness across cultures. 11,12
The benefits of napping for
waking performance such as improved neurobehavioral
performance and alertness have been systematically
reviewed in healthy adults. 13
However, longer naps (eg, 30
minutes or longer) can cause sleep inertia, which is associ-
ated with confusion, grogginess, and deficits to cognitive
performance. 14
Some important factors, such as frequency,
length, and temporal placement of naps should be taken
into consideration in order to understand the consequences
of napping. 13
Napping behavior and its effect on nighttime sleep
remain less well studied in the college population. Few
researchers have considered how napping behavior is
related to nighttime sleep. The goal of the present study
was to characterize the habit of napping, including self-
reported nap frequency, length, and timing, and examine its
relationship with nighttime sleep (as measured by self-
reported sleep duration and quality) in a group of college
students in the United States. Understanding the effect of
napping on nighttime sleep will help planners develop strat-
egies to promote sleep quality and, ultimately, improve
overall health and academic performance in young adults.
METHODS
Data Collection
This study used a Web-based survey (Qualtrics Survey
Program) to characterize the self-reported habit of napping
Dr Ye, Ms Hutton Johnson, and Ms Keane are with the William F. Connell School of Nursing at Boston College in Chestnut Hill, Massachusetts. Mr Manasia is with the Memorial Sloan-Kettering Cancer Center in New York, New York. Dr Gregas is with Research Services at Boston College in Chestnut Hill, Massachusetts.
Copyright � 2015 Taylor & Francis Group, LLC
88
JOURNAL OF AMERICAN COLLEGE HEALTH, VOL. 63, NO. 2
and its relationship with nocturnal sleep in college students.
Undergraduate students were invited via e-mail to partici-
pate in an anonymous online survey. With the approval of
the university’s Institutional Review Board, e-mail
addresses of 2,000 undergraduate students were obtained
from the Office of Institutional Research. This was a ran-
dom sample of currently registered undergraduates in terms
of sex, race, and enrolled schools. Following principles out-
lined by Dillman and colleagues, 15
4 e-mails were sent out
to these students: an introductory e-mail on day 1 that intro-
duced the study and advised that another e-mail would
arrive with participation details, an e-mail on day 4 that
included the link to the survey, a reminder e-mail on day 7
encouraging participation, and the final reminder on day
11. Each participant gave informed consent by reading the
consent form online and putting his or her initials in a des-
ignated box to indicate agreement to participate. Partici-
pants who completed the survey were invited to enter a
lottery to receive an online gift certificate. The survey was
conducted in April 2010, at least 1 month prior to the week
of final examinations so that students’ responses were not
influenced by potentially severe sleep deprivation before
final examinations. A total of 440 students participated and
completed the survey, yielding a response rate of 22%.
Measurements
Participants completed a survey including multiple-
choice items and open-ended questions. The open-ended
questions asked for descriptions of perceived benefits, bar-
riers encountered, and suggested interventions to improve
sleep quality, and will be reported separately. The current
report provides results from the multiple-choice items in
the survey, examining the habit of self-reported napping
and sleep quality in college students.
Sleep quality was measured using the Pittsburgh Sleep
Quality Index (PSQI). 16
It is a 19-item self-rating question-
naire designed to assess sleep quality and disturbances over
a 1-month time interval and includes 7 “components”: sub-
jective sleep quality, sleep latency, sleep duration, habitual
sleep efficiency, sleep disturbances, use of sleeping medica-
tion, and daytime dysfunction. The sum of the component
scores yields 1 global score, ranging from 0 to 21. At the
cutoff point of 5, the PSQI has a sensitivity of 89.6% and a
specificity of 86.5% in distinguishing good (PSQI global
score � 5) and poor sleepers (PSQI global score > 5).16 The PSQI has a high degree of internal constancy and test-
retest reliability. 16
The PSQI has been used to examine
sleep quality in the college student population. 17,18
In this
study, only the PSQI global score was reported and used in
data analyses. In addition to administering the PSQI, sup-
plemental survey questions were added to gain more infor-
mation about students’ weekday versus weekend sleep
schedules and students’ self-identification of “early bird”
(go to bed early and get up early) or “night owl” (go to bed
late and get up late) routines.
Three questions elicited descriptions of nap habits,
including napping frequency, average length, and typical
time of naps. Participants were first asked, “Do you usually
take naps?” with 4 possible responses: not during the past
month, less than once per week, once or twice per week,
and 3 or more times per week. Those who responded other
than “not during the past month” were then asked to spec-
ify: “How long were your naps on average?” (0.5 hours or
less, 1 hour, 1.5 hours, 2 hours, over 2 hours) and “What
was the typical time for you to take naps?” (morning,
12–3 PM, 3–6 PM, and 6–9 PM).
The survey included questions about demographics,
general health (excellent, very good, good, fair, or
poor), and mood/energy level (using a 10-point scale,
with ¡5 being very depressed or fatigued and C5 very elated or energetic). Academic performance was ascer-
tained by self-reported grade point average (GPA) on a
4.0 scale. The students were also asked how satisfied
they were with their amount of sleep on nights before
class and if they missed class or were late for school
because of oversleeping.
Statistical Analysis
The sample characteristics were evaluated using sum-
mary statistics, with means, standard deviations, or pro-
portions as appropriate. For each continuous variable, an
analysis of variance was performed with napping fre-
quency, length, and timing as predictors. If the likeli-
hood-ratio test for the predictors was significant,
pairwise contrasts were examined. Tukey’s honest signif-
icant difference method was used to adjust for multiple
comparisons. 19
Counts among student groups were com-
pared using chi-square analyses. Pearson correlations
were used to examine the associations between continu-
ous variables. Multiple regression analyses were per-
formed to determine the relationship between self-
reported napping habits and sleep quality, controlling for
identified pertinent covariates including age and sex. For
all analyses, a 2-sided significance level of a D .05 was used. Data analyses were conducted using the Statistical
Package for the Social Sciences version 18.0 software
(SPSS, Chicago, Illinois).
RESULTS
Sample Demographic Characteristics and Sleep Habits
As indicated in Table 1, the majority of the sample
consisted of college-aged (20.0 § 1.3 years) female (66.4%), white (80.2%), non-Hispanic (90.9%) students.
Approximately 19% of the students were overweight or
obese, with a body mass index (BMI), calculated based
upon self-reported height and weight, greater than or
equal to 25 kg/m 2 . Over half (58.7%) self-rated their
general health as very good or excellent. On a scale of
¡5 to 5, the students rated their average mood/energy
Napping and Nighttime Sleep
VOL 63, FEBRUARY/MARCH 2015 89
level as 1.6 § 2.0, with the majority (81.8%) rating the level equal to or higher than 0.
Sleeping habits and sleep quality for the entire sample
are described in the column of “Total cohort” of Table 2.
Over half of the respondents (59.7%) were classified as
poor sleepers because they had a PSQI score higher than 5.
The students in the sample slept an average of 1.7 hours
longer during the weekend than on weekdays (8.3 § 1.4 vs 6.7 § 1.2; p < .001). Approximately two thirds of the stu- dents (66.3%) identified themselves as “night owls.” The
self-reported GPA was negatively correlated with the PSQI
score (r D ¡.163, p D .002), indicating that self-reported poorer sleep quality was associated with poorer academic
performance. In addition, higher PSQI score (poorer sleep
quality) was significantly correlated with shorter self-
reported nightly sleep duration (r D ¡.516, p < .001) and greater difference in sleep hours between school days and
weekends (r D .224, p < .001).
Frequency of Naps and Sleep Quality
Sleep quality and sleep habits for groups by self-reported
napping frequency are reported in Table 2. Taking naps
during the month prior to completing the survey was
reported in 75% of the participants, with 42.9% reporting
having napped at least once per week. The PSQI score sig-
nificantly differed among the 4 nap-frequency groups
(p D .047). Students who reported napping 3 or more times per week during the month prior to completing the survey
had the highest PSQI score, indicating the poorest sleep
quality (7.0 § 2.5), which was, on average, 1.2 points
higher than those who reported they did not nap (5.8 § 3.3; p D .052).
Among the 4 nap-frequency groups, significant differen-
ces were also observed in the disparities in self-reported
sleep hours between school days and the weekend
(p D .039), in the rate of being “night owls” (p < .001), being satisfied with the amount of sleep on nights before
class (p D .002), and missing or being late for school because of oversleeping (p D .008). Frequent nappers (� 3/ week) had a significantly greater difference in self-reported
school day sleep hours and weekend sleep hours than non-
nappers (2.1 § 2.1 vs 1.3 § 1.6; p D .029). In addition, among the 4 nap-frequency groups, frequent nappers were
the most likely to identify themselves as “night owls”
(77.6%) and report missing or being late for school because
of oversleeping (62.7%), but were the least likely to feel
satisfied with the amount of sleep they got on nights before
class (25.4%).
Length of Naps and Sleep Quality
Among those who reported napping during the month
prior to completing the survey (n D 330 of 440), sleep qual- ity and sleep habit for 5 nap-length groups are reported in
Table 3. The mean PSQI score was significantly different
among the groups (p D .017). Students who reported nap- ping over 2 hours on average had a 2-point higher PSQI
score compared with those who reported napping for 1 hour
(7.9 § 3.8 vs 5.9 § 2.4; p D .036). Compared with shorter nappers, students who self-
reported taking longer naps slept less during school nights
(p D .011) but slept longer during the weekend (p D .001), had a greater difference in sleep duration between school
days and weekends (p < .001), and were more likely to
identify themselves as “night owls” (p D .004). For exam- ple, 87% of the students who reported napping for longer
than 2 hours per day considered themselves “night owls,”
but this dropped to 53.4% for those who reported napping
0.5 hours or less. In addition, longer nappers were less
likely to be satisfied with the amount of sleep they had dur-
ing the nights before class (p D .001) and were more likely to be late to or miss class because of oversleeping (p D .001). Additionally, the GPA was significantly different
among nap-length groups (p D .008), with students who napped longer having a lower GPA.
Timing of Naps and Sleep Quality
Sleep quality and sleep habits based on the timing of
naps among students who napped during the month prior to
completing the survey are reported in Table 4. The majority
of students reported napping in the afternoon, with 23%
between 12 and 3 PM and 67% between 3 and 6 PM. Students
who napped between 6 and 9 PM reported fewer hours of
sleep (5.7 § 1.2) on school nights compared with students who napped at other times (p D .002), namely, those who
TABLE 1. Demographic Characteristics of the Study Sample (N D 440) Characteristic % M SD
Female 66.4 White 80.2 Hispanic 9.1 Age, years 20.0 1.3 Body mass index, kg/m
2 23.0 3.2
Overweight or obese 19.3 Year in school Freshman 26.1 Sophomore 29.3 Junior 19.8 Senior 24.8
Self-rated general health Excellent 11.4 Very good 47.3 Good 33.8 Fair 6.6 Poor 0.7
Mood/Energy level 1.6 2.0
Ye et al
90 JOURNAL OF AMERICAN COLLEGE HEALTH
T A B L E 2 . S le e p Q u a li ty
a n d S le e p H a b it fo r th e E n ti re
C o h o rt a n d b y N a p p in g F re q u e n c y
T o ta l c o h o rt
(N D
4 4 0 ; 1 0 0 % )
N o n a p p in g
(n D
1 1 0 ; 2 5 % )
N a p p in g
< 1 /w e e k
(n D
1 4 1 ; 3 2 % )
N a p p in g
1 – 2 /w e e k
(n D
1 2 2 ; 2 7 .7 % )
N a p p in g
�3 /w e e k
(n D
6 7 ; 1 5 .2 5 % )
S a m p le c h a ra c te ri st ic
% M
S D
% M
S D
% M
S D
% M
S D
% M
S D
p v a lu e
P S Q I g lo b a l
6 .4
2 .9
5 .8
a 3 .3
6 .6
2 .9
6 .2
2 .5
7 .0
a 2 .5
.0 4 7
P o o r sl e e p e r (P S Q I
g lo b a l > 5 )
5 9 .7
4 8 .9
6 6 .1
5 8 .9
6 4 .8
.0 7 7
A v e ra g e sl e e p
d u ra ti o n
6 .9
1 .2
6 .8
1 .2
7 .0
1 .2
7 .0
1 .1
6 .8
1 .1
.3 2 9
S le e p h o u rs – sc h o o l
n ig h t
6 .7
1 .2
6 .7
1 .2
6 .7
1 .2
6 .6
1 .2
6 .5
1 .1
.7 0 1
S le e p h o u rs – w e e k e n d
8 .3
1 .4
8 .1
1 .3
8 .3
1 .3
8 .4
1 .4
8 .6
1 .5
.0 5 9
D if fe re n c e in
sl e e p
h o u rs b e tw e e n
sc h o o l d a y s a n d
w e e k e n d
1 .7
1 .7
1 .3
b 1 .6
1 .6
1 .6
1 .8
1 .7
2 .1
b 2 .1
.0 3 9
N ig h t o w l
6 6 .3
5 3 .6
6 1 .4
7 7 .0
7 7 .6
.0 0 0
S a ti sfi e d w it h th e
a m o u n t o f sl e e p o n
n ig h ts b e fo re
c la ss ?
4 1 .9
5 4 .5
3 9 .7
4 2 .1
2 5 .4
.0 0 2
M is se d /l a te fo r c la ss
b e c a u se
o f
o v e rs le e p in g
4 9 .1
3 8 .2
4 6 .8
5 4 .1
6 2 .7
.0 0 8
G P A
3 .4
0 .4
3 .4
0 .3
3 .4
0 .3
3 .4
0 .4
3 .3
0 .4
.1 0 1
N o te . P S Q I D
P it ts b u rg h S le e p Q u a li ty
In d e x ; G P A = g ra d e p o in t a v e ra g e .
a T h e
P S Q I
g lo b a l
sc o re
w a s
lo w e r
in th o se
w h o
d id
n o t
n a p
d u ri n g
th e
p a st
m o n th
c o m p a re d
w it h
th o se
w h o
n a p p e d
3 o r
m o re
ti m e s
p e r
w e e k
(p D
.0 5 2 ).
b T h e d if fe re n c e in
sl e e p h o u rs b e tw e e n w e e k e n d a n d w e e k d a y s w a s si g n ifi c a n tl y g re a te r in
th o se
w h o d id
n o t n a p d u ri n g th e p a st m o n th
c o m p a re d w it h th o se
w h o n a p p e d 3 o r m o re
ti m e s p e r w e e k (p
D .0 2 9 ).
VOL 63, FEBRUARY/MARCH 2015 91
Napping and Nighttime Sleep
T A B L E 3 . S le e p Q u a li ty
a n d S le e p H a b it b y L e n g th
o f N a p s
0 .5
h o u rs
o r le ss
(n D
5 9 ; 1 7 .9 %
a m o n g a ll n a p p e rs )
1 h o u r
(n D
1 1 5 ; 3 4 .8 %
a m o n g a ll n a p p e rs )
1 .5
h o u rs
(n D
8 5 ; 2 5 .8 %
a m o n g a ll n a p p e rs )
2 h o u rs
(n D
4 7 ; 1 4 .2 %
a m o n g a ll n a p p e rs )
> 2 h o u rs
(n D
2 3 ; 7 .0 %
a m o n g a ll n a p p e rs
S a m p le c h a ra c te ri st ic
% M
S D
% M
S D
% M
S D
% M
S D
% M
S D
p v a lu e
P S Q I g lo b a l
6 .5
2 .5
5 .9
a 2 .4
7 .0
2 .5
6 .9
3 .1
7 .9 a
3 .8
.0 1 7
P o o r sl e e p e r
6 5 .2
6 0 .2
6 6 .2
6 5 .8
6 1 .1
.9 3 4
A v e ra g e sl e e p
d u ra ti o n
7 .0
1 .1
7 .1
1 .0
6 .9
1 .1
6 .8
1 .2
6 .7
1 .5
.3 0 0
S le e p h o u rs – sc h o o l
n ig h t
6 .7
1 .1
6 .8
b 1 .1
6 .7
1 .2
6 .3
1 .1
6 .1 b
1 .2
.0 1 1
S le e p h o u rs – w e e k e n d
8 .1
c 1 .2
8 .3
c 1 .4
8 .3
1 .3
9 .0
c 1 .4
9 .2 c
1 .6
.0 0 1
D if fe re n c e in
sl e e p
h o u rs b e tw e e n
sc h o o l d a y s a n d
w e e k e n d
1 .5
1 .6
1 .4
1 .6
1 .6
1 .8
2 .6 d
1 .9
3 .1 d
1 .5
.0 0 0
N ig h t o w l
5 3 .4
6 7 .0
7 7 .6
7 8 .7
8 7 .0
.0 0 4
S a ti sfi e d w it h th e
a m o u n t o f sl e e p o n
n ig h ts b e fo re
c la ss ? (y e s)
3 3 .9
4 4 .3
4 7 .1
1 7 .4
1 7 .4
.0 0 1
M is se d /l a te fo r c la ss
b e c a u se
o f
o v e rs le e p in g (y e s)
4 4 .1
4 4 .3
5 2 .9
7 2 .3
7 8 .3
.0 0 1
G P A
3 .5
0 .3
3 .5
0 .3
3 .4
0 .4
3 .3
0 .5
3 .3
0 .4
.0 0 8
N o te . P S Q I D
P it ts b u rg h S le e p Q u a li ty
In d e x ; G P A D
g ra d e p o in t a v e ra g e .
a T h o se
w h o n a p p e d lo n g e r th a n 2 h o u rs h a d a si g n ifi c a n tl y h ig h e r P S Q I g lo b a l sc o re
th a n th o se
w h o n a p p e d fo r 1 h o u r (p
D .0 3 6 ).
b T h o se
w h o n a p p e d lo n g e r th a n 2 h o u rs h a d si g n ifi c a n tl y sh o rt e r sl e e p d u ra ti o n d u ri n g sc h o o l n ig h t th a n th o se
w h o n a p p e d fo r 1 h o u r (p
D .0 3 5 ).
c T h o se
w h o n a p p e d fo r h a lf a n h o u r o r le ss
h a d a si g n ifi c a n tl y le ss
sl e e p h o u r d u ri n g w e e k e n d th a n th o se
w h o n a p p e d 2 h o u rs (p
D .0 1 3 ) o r w h o n a p p e d lo n g e r th a n 2 h o u rs (p
D .0 1 2 ). T h o se
w h o n a p p e d fo r
1 h o u r h a d a si g n ifi c a n tl y le ss
sl e e p h o u r d u ri n g w e e k e n d th a n th o se
w h o n a p p e d 2 h o u rs (p
D .0 2 4 ) o r w h o n a p p e d lo n g e r th a n 2 h o u rs (p
D .0 2 2 ).
d T h o se
w h o n a p p e d fo r 2 h o u rs o r lo n g e r h a d si g n ifi c a n tl y g re a te r d if fe re n c e s in
sl e e p h o u rs b e tw e e n sc h o o l d a y s a n d w e e k e n d c o m p a re d w it h th o se
w h o n a p p e d 0 .5
h o u rs o r le ss , 1 h o u r, o r 1 .5
h o u rs (a ll p
v a lu e s <
.0 1 ).
92 JOURNAL OF AMERICAN COLLEGE HEALTH
Ye et al
T A B L E 4 . S le e p Q u a li ty
a n d S le e p H a b it b y T im
in g o f N a p s
M o rn in g
(n D
7 ; 2 .1 %
a m o n g
a ll n a p p e rs )
1 2 – 3
P M
(n D
7 6 ; 2 3 .0 %
a m o n g a ll n a p p e rs )
3 – 6
P M
(n D
2 2 1 ; 6 7 .0 %
a m o n g a ll n a p p e rs )
6 – 9
P M
(n D
2 1 ; 6 .4 %
a m o n g a ll
n a p p e rs )
S a m p le c h a ra c te ri st ic
% M
S D
% M
S D
% M
S D
% M
S D
p v a lu e
P S Q I g lo b a l
7 .3
2 .7
6 .6
2 .4
6 .4
2 .8
7 .3
2 .7
.5 1 0
P o o r sl e e p e r
8 3 .3
6 9 .4
5 8 .1
7 8 .9
.0 9 9
A v e ra g e sl e e p
d u ra ti o n
6 .6
0 .8
7 .0
1 .3
7 .0
1 .0
6 .5
1 .4
.1 7 6
S le e p h o u rs – sc h o o l
n ig h t
6 .6
0 .7
6 .7
a 1 .2
6 .7
a 1 .1
5 .7
a 1 .2
.0 0 2
S le e p h o u rs – w e e k e n d
7 .9
0 .9
8 .6
1 .4
8 .4
1 .3
8 .1
1 .8
.4 0 1
D if fe re n c e in
sl e e p
h o u rs b e tw e e n
sc h o o l d a y s a n d
w e e k e n d
1 .3
0 .6
1 .8
1 .8
1 .7
1 .7
2 .4
2 .6
.2 5 5
N ig h t o w l
2 8 .6
7 1 .1
7 0 .5
8 1 .0
.0 9 2
S a ti sfi e d w it h th e
a m o u n t o f sl e e p o n
n ig h ts b e fo re
c la ss ? (y e s)
2 8 .6
3 5 .5
4 1 .4
1 4 .3
.0 6 3
M is se d /l a te fo r c la ss
b e c a u se
o f
o v e rs le e p in g (y e s)
5 7 .1
5 7 .9
4 7 .5
8 5 .7
.0 0 4
G P A
3 .6
0 .2
3 .5
0 .4
3 .4
0 .4
3 .3
0 .5
.3 2 4
N o te . P S Q I D
P it ts b u rg h S le e p Q u a li ty
In d e x ; G P A D
g ra d e p o in t a v e ra g e .
a S tu d e n ts w h o n a p p e d b e tw e e n 6 a n d 9
P M h a d a si g n ifi c a n tl y sh o rt e r sl e e p d u ra ti o n d u ri n g sl e e p n ig h t c o m p a re d w it h th o se
w h o n a p p e d b e tw e e n 1 2 a n d 3
P M (p
D .0 0 2 ) a n d th o se
w h o n a p p e d b e tw e e n 3 a n d
6 P M (p
D .0 0 1 ).
VOL 63, FEBRUARY/MARCH 2015 93
Napping and Nighttime Sleep
napped between 12 and 3 PM (6.7 § 1.2; p D .002) and between 3 and 6 PM (6.7 § 1.1; p D .001). In addition, these late nappers were significantly more likely to miss or be
late for class due to oversleeping compared with students in
other nap-timing groups (p D .004).
Overall Napping Habits (Frequency, Length, and Timing) and Sleep Quality
Among all the students who reported napping in the
month prior to the survey, the relationships of 3 aspects of
self-reported napping habits with nocturnal sleep quality
were concurrently examined using multiple regression anal-
yses. Among the demographic variables (including age,
sex, BMI, race, ethnicity, year in school, and enrolled
school), only age and sex were significantly associated with
the PSQI score and remained as covariates in the final
regression model (Table 5). Controlling for age and sex,
the greater average length of nap was significantly associ-
ated with a higher PSQI score (b D .187, p D .003). We also found that self-rated general mood and energy level
significantly differed among the 5 nap-length groups, with
those who reported napping longer having a lower mood
and energy level (p D .007).
COMMENT
This study characterized 3 important aspects of self-
reported napping behavior, including frequency, length,
and timing, and its relationship with nighttime sleep in a
group of American college students. Special attention needs
to be given to frequent (3 or more times per week), long
(over 2 hours), or late (between 6 and 9 PM) nappers who
have a high risk of suffering poor nighttime sleep quality,
severe sleep deprivation, and the associated poor academic
performance.
This study provides further evidence that napping is a
common behavior in college students. The majority of the
sample (75%) reported napping during the month prior to
completing the survey, with 42.9% reported having napped
at least once per week. This is similar to previous reports
from college students in Spain 11
and Hong Kong. 20
Although it has been estimated that as many as 75% of
healthy adults take naps, people choose to nap for a variety
of reasons: replacement naps in response to perceived
sleepiness; appetitive naps without regard to insufficient
sleep but for enjoyment; and prophylactic naps in advance
of sustained wakefulness or in preparation for sleep loss. 21
In our study, self-reported nappers, particularly those fre-
quent, long, and late nappers, reported less sleep on school
nights and tended to sleep longer during the weekend. This
lends support to the premise that these naps could be
replacement naps, which are likely to be used as a coping
strategy against weeknight insufficient sleep and daytime
sleepiness by college students. As supported by a previous
epidemiological survey on sleep in a representative sample
of Italian adolescents, an evening circadian preference—or
being a “night owl”—can be significantly associated with
napping. 22
The majority of the students in our study
(66.3%) self-identified as “night owls,” and this rate was
even higher for those who reported being frequent (77.6%),
long (87%), and late (81%) nappers. Being “night owls”
can predispose students to partial sleep deprivation, result-
ing in an increased reliance on replacement naps. In addi-
tion, underlying sleep disorders may contribute to daytime
sleepiness and poor daily functioning, and students tend to
compensate by napping. This is supported by the observed
strong association of napping with sleep apnea in a popula-
tion-based study in Spain. 23
Why college students nap and
whether napping could be regarded as a marker of underly-
ing sleep disorders deserve further investigation.
Our findings offer empirical support for the association
between the habit of napping and sleep quality. There is a
growing concern about college students’ poor sleep quality,
with irregular sleep patterns and sleep deprivation being
very common in these young adults. 12,20
It is alarming that
based upon PSQI scores, 59.7% of the students in our sam-
ple were classified as poor sleepers, and that sleep quality
was even worse for those who reported napping during the
month prior to completing the survey. The underlying
causes for the poor sleep in college students may be multi-
factorial. Individual factors such as poor sleep hygiene
associated with inadequate sleep knowledge could lead to
poor sleep quality in college students. 24 The early start time
of morning classes can also contribute to shorter sleep
TABLE 5. Relationship Between Napping Habits (Frequency, Length, and Timing) and Sleep Quality
Variable Standardized coefficient (b) Significance (p value)
Sex ¡.151 .015* Age .161 .008
*
Napping frequency ¡.012 .846 Length of nap(s) .187 .003
*
Timing of nap(s) .009 .878
Note. For the regression model, total R 2 D .074, F D 4.083 (df D 5), p D .001.
* p < .05.
94 JOURNAL OF AMERICAN COLLEGE HEALTH
Ye et al
length on weekdays and compensatory sleep during
weekends. 25
The effect of napping on nighttime sleep may be com-
plex. Napping can alter the sleep–wake cycle, which is
associated with hypothalamic–pituitary–adrenal axis dysre-
gulation in young adults, and may lead to negative health
consequences such as depression, decreased glucose toler-
ance and insulin sensitivity, altered adrenal function, and
increased evening cortisol levels. 26,27
When considering
frequency, length, and timing of napping concurrently, we
found that longer naps were significantly associated with
poorer overall sleep quality when controlling for age and
sex. Long naps have been shown to be less efficient than
short naps in improving cognitive performance and subjec-
tive alertness. 28 Sleep inertia is more likely to follow longer
naps, which consist of more slow wave sleep. 29
Sleep iner-
tia is the experience of impaired performance and/or dis-
orientation immediately after awaking from sleep. 30
The
effect of sleep inertia can last up to 4 hours after awaken-
ing 31
and may influence nocturnal sleep quality particularly
for those late nappers who take long naps. In addition, tak-
ing long naps can be a sign of depression, which may
directly impair sleep quality. This is supported by our
observation that students who reported napping longer
reported a lower mood and energy level.
Our findings suggest that for those who nap habitually,
taking a shorter nap should be considered to enhance night-
time sleep quality. Healthy young adults should ideally nap
for approximately 10 to 20 minutes, with benefits in mood,
alertness, and cognitive performance. 32,33
Taking short
naps has been recommended in workplace settings, where
performance immediately upon awakening is normally
required. 13
Power naps, typically defined as sleep episodes
of less than 20 minutes, have been discussed as a potential
countermeasure to fatigue and sleepiness. 34
Amin et al 35
reported that a short (up to 20 minutes) mid-day nap
improved cognitive functioning and alertness among medi-
cal residents. Pilcher and colleagues 34
found that in a group
of healthy young and middle-aged adults, approximately
half of the participants reported napping for less than 20
minutes. In contrast, the majority of the students in our
sample reported napping much longer. It is possible that the
participants were less likely to remember short naps when
they were surveyed about their sleep habits. A daily log, as
adopted in the study by Pilcher and colleagues, 34
may have
allowed a more accurate assessment of sleep habits.
The timing of a nap also is known to have a significant
effect on nighttime sleep. An evening nap can alter one’s
circadian rhythms, leading to disrupted sleep and less noc-
turnal sleep. 36 Although sleep tendency usually increases in
the afternoon, researchers studying healthy young adults
have not identified a “best” time to nap. As suggested by
Milner and Cote, 13
the best time to nap might depend on
various factors, such as individual sleep need, morning-
ness-eveningness tendencies, quality of sleep during the
nap, and sleep quality of the previous night.
We found that students who reported napping more fre-
quently, or who reported being long or late nappers, had
either a lower GPA or were more likely to miss or be late to
class due to oversleeping. The effect of napping on aca-
demic performance in college students is likely to be medi-
ated by nighttime sleep quality, sleep duration, and sleep/
wake schedules. Consistent with our findings, poor sleep
quality, together with shortened sleep duration, late to-bed
and rise times, and erratic sleep/wake schedules, has been
demonstrated to negatively affect academic performance
for adolescents from middle school through college. 9,37
Poorer nighttime sleep quality and worse sleep deprivation
in frequent, long, and late nappers may lead to overall
poorer daily functioning and cognitive performance, which
can contribute to impaired academic performance, among
other negative consequences.
Limitations
Some limitations in this study need to be considered. A
causal relationship cannot be inferred from the cross-
sectional survey data collected in this study. The bidirec-
tional relationship between the napping behavior and night-
time sleep should be noted. In the present study,
retrospective subjective reports of napping and sleep pat-
terns were utilized. Although it has been suggested that
self-reported sleep survey data are as reliable as objective
measures in adolescents, 38
sleep–wake diaries, polysom-
nography, or actigraphy measurements could possibly pro-
vide more valid assessments for napping and nighttime
sleep. Other aspects of napping, such as the number of naps
per day and the individual experience of napping, may also
have an effect on nighttime sleep. Further studies could be
designed to examine these issues. We compared our final
sample with the undergraduate student population in this
university and noticed that the proportion of females in the
sample was higher compared with that in the overall student
body (66.4% vs 52%). It is possible that females were more
likely to respond to the online survey. Although the major-
ity of the questions of the online survey were from the
highly validated PSQI, the reliability or validity for other
survey questions were not tested, including the 3 questions
describing napping habits, the supplemental questions of
sleep habits (eg, weekday vs weekend sleep schedules,
being “early bird” or “night owl”), and questions about gen-
eral health and mood/energy level. Future studies using val-
idated instruments are needed to confirm our findings. It is
hoped that our study can guide the development of a valid
and reliable questionnaire evaluating napping behavior for
future investigations.
Conclusion
In summary, this study documented the habit of napping
by frequency, length, and timing and assessed how napping
VOL 63, FEBRUARY/MARCH 2015 95
Napping and Nighttime Sleep
may affect nighttime sleep in a selected group of college
students. Given its high prevalence and association with
nighttime sleep, napping behavior should be assessed for
college students, at least for those who show an unexpected
change in their academic performance. One of the most
interesting findings is the demonstrated worse nighttime
sleep quality, more severe sleep deprivation, and overall
poorer academic performance in students who were self-
reported frequent, long, or late nappers. Notably, the signif-
icant implications of napping habits to college students’
nighttime sleep quality, their GPA, and class absence or tar-
diness should be taken seriously by academic administra-
tors and health providers. Although napping has been
routinely assessed in students presenting with sleep and/or
mood disturbance, current practice is largely limited to sim-
ply asking whether or not the students take naps. We rec-
ommend that it is critical to include specific questions
examining frequency, length, and timing of napping. A
valid and reliable questionnaire evaluating these aspects of
napping is needed for future research and practice. Further
evaluation and tailored interventions are needed for college
students who are identified to be frequent, long, or late nap-
pers. Educational and behavioral programs aiming to
improve sleep quality in college students can also benefit
from specific instructions about napping. Researchers
should examine the impetus for napping and the underlying
causes of differences in self-reported sleep habits and qual-
ity, including the role of consumption of caffeine, alcohol,
and recreational drugs, as well as the influence of technol-
ogy use late into night (eg, cell phones, social media, Inter-
net) on college campuses. Based on a more nuanced
understanding of these factors, interventional strategies at
the individual and institutional levels aimed at improving
college students’ sleep could be created and tested for
effectiveness.
FUNDING
No funding was used to support this research and/or the
preparation of the manuscript.
CONFLICT OF INTEREST DISCLOSURE
The authors have no conflicts of interest to report.
The authors confirm that the research presented in this
article met the ethical guidelines, including adherence to
the legal requirements, of the United States and received
approval from the Institutional Review Board of Boston
College.
NOTE
For comments and further information, address corre-
spondence to Lichuan Ye, PhD, RN, Assistant Professor,
Boston College, William F. Connell School of Nursing,
Cushing Hall 423, 140 Commonwealth Avenue, Chestnut
Hill, MA 02467, USA (e-mail: yel@bc.edu).
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Received: 7 April 2014 Revised: 1 October 2014
Accepted: 12 October 2014
VOL 63, FEBRUARY/MARCH 2015 97
Napping and Nighttime Sleep
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