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SLEEP DEPRIVATION INDUCED ANXIETY AND ANAEROBIC PERFORMANCE
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1Department of Physiology, Trakya University Faculty of Medicine,
2Kırkpınar Physical Education and Sport Department, Trakya University ,
3Department of Bioistatistics, Trakya University Faculty of Medicine
4Department of Psychiatry, Trakya University Faculty of Medicine, Edirne,
Turkey.
| Received |
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08 June 2007 |
| Accepted |
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24
September 2007 |
| Published |
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01
December 2007 |
©
Journal of Sports Science and Medicine (2007) 6, 532- 537
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| ABSTRACT |
| The aim of this study was to investigate the effects of sleep
deprivation induced anxiety on anaerobic performance. Thirteen volunteer
male physical education students completed the Turkish version of
State Anxiety Inventory and performed Wingate anaerobic test for three
times: (1) following a full-night of habitual sleep (baseline measurements),
(2) following 30 hours of sleep deprivation, and (3) following partial-night
sleep deprivation. Baseline measurements were performed the day before
total sleep deprivation. Measurements following partial sleep deprivation
were made 2 weeks later than total sleep deprivation measurements.
State anxiety was measured prior to each Wingate test. The mean state
anxiety following total sleep deprivation was higher than the baseline
measurement (44.9 ± 12.9 vs. 27.6 ± 4.2, respectively, p = 0.02) whereas
anaerobic performance parameters remained unchanged. Neither anaerobic
parameters nor state anxiety levels were affected by one night partial
sleep deprivation. Our results suggest that 30 hours continuous wakefulness
may increase anxiety level without impairing anaerobic performance,
whereas one night of partial sleep deprivation was ineffective on
both state anxiety and anaerobic performance.
KEY
WORDS: Psychophysiological
disorders, mood, insufficient sleep, muscle fatique.
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| INTRODUCTION |
|
Evidence suggests athletes worry about the effects of inadequate
sleep on performance (Leger et al., 2005)
although sleep deprivation on physical performance (e.g. anaerobic
power, muscle strength, endurance, physiological responses such
as heart rate, ventilation, oxygen consumption) is not clearly understood
(Martin, 1981;
1986;
Rodgers et al., 1995;
Souissi et al., 2003;
Youngstedt and O'Connor, 1999). Rodgers et al., 1995 reported that 48 hours period of sleep deprivation significantly
decreased the physical work tasks requiring 30-45% VO2max
without affecting anaerobic power. Further, Souissi et al., 2003
demonstrated that duration of sleepless period may be important
as peak power was not affected after 24 hours sleep deprivation
but significantly decreased after 36 hours of wakefulness.
In contrast, it is well established that sleep deprivation can result
in impairments in affective states (e.g. increased anxiety, depressed
mood, anger, tension, frustration and irritability) and cognitive
functions (JrLeDuc et al., 2000;
Orton and Gruzelier, 1989;
Scott et al., 2006).
Martin and Gaddis (1981)
demonstrated that 30 hours sleep deprivation significantly affected
psychological responses without affecting physical performance.
According to a recent study, it was found that 56 hours sleep deprivation
was associated with a statistically significant increase in self
reported symptoms of anxiety (Kahn-Greene et al., 2007).
The relationship between anxiety and athletic performance has been
extensively studied (Craft et al., 2003;
DeMoja and DeMoja, 1986;
Hogg, 1980;
Hume et al., 1993;
Jones and Hardy, 1988;
Kais and Raudsepp, 2004;
Pijpers et al., 2005).
Additionally, various theoretical models have been proposed to describe
the relationship between anxiety and performance (Raglin, 1992;
Thelwell and Maynard, 1996;
Turner and Raglin, 1996).
Inconsistent results have been obtained for the effect of anxiety
on athletic performance. Some studies report negative correlation
between anxiety and athletic performance (DeMoja and DeMoja, 1986;
Hume et al., 1993).
For instance, Hume et al., 1993
demonstrated a significant negative correlation between athletic
attainment and anxiety level in 106 female gymnasts. In contrast,
some studies showed positive correlation, whereby anxiety appeared
to have helped performance (Kais and Raudsepp, 2004;
Parfitt et al., 1995;
Parfitt and Pates, 1999).
For example, Parfitt and Pates, 1999
showed that increase in somatic anxiety is associated with increase
in anaerobic power.
A factor that could influence the strength of anxiety-performance
relationships not considered adequately in the literature is the
effect of sleep deprivation. Previous studies demonstrated that
sleep deprivation is associated with increased anxiety in healthy
young adults (Dinges et al., 1997;
Kahn-Greene et al., 2007;
Sagaspe et al., 2006).
Sleep deprivation is associated with higher state anxiety levels
which in turn alter athletic performance. Pedlar et al., 2007
demonstrated that it was possible to continuously decrease sleep
time to an extremely low level for a prolonged period (44 days)
and simultaneously maintain a very high work load; however, this
pattern may have adverse affects on mood. Therefore, it has been
thought that additional studies of sleep deprivation may help to
elucidate the association between anxiety and athletic performance.
We hypothesize that duration of sleep deprivation in the night preceding
anaerobic athletic event is an effective variable in determining
anxiety level and thus anaerobic performance. The aim of this study
was to investigate the possible short-term total and partial sleep
deprivation induced anxiety on anaerobic performance parameters
such as peak power and mean power obtained from the 30-second Wingate
Test in the same study population.
| METHODS |
|
Participants
Thirteen healthy male students attending school of physical
education accepted to participate in the study. As the Wingate
test requires maximum power, only students who exercise regularly
were accepted to the study. In addition just the males were
included in the study in order to assure that the findings
following sleep deprivation are not affected from gender differences
(Caldwell and Leduc, 1998).
Details of the study were explained to each participant and
signed informed consents were obtained. The study was approved
by the local ethics committee of Trakya University. A self-administered
questionnaire was used to assess age, weight, height, with
their participation age to sports, and the amount of training
per week. The mean (±SD) age, height, BMI, participation age
in sports, duration of training and the amount of training
of the participants were given in Table
1. BMI was calculated as weight in kilograms per height
in square meters. Since participants were unfamiliar with
the procedures, the Wingate Anaerobic Test was applied to
all participants two weeks prior to the experimental trials
in order to provide familiarity.
Participants also kept a diary of their activities during
the three days before the baseline night. Participants' time
of going to bed varied between 10 00 p.m. and 11 00 p.m. The
time of waking up varied between 07 00 a.m. and 08 00 a.m.
Inclusion
criteria
All participants were non-smokers and they took no medication
or alcohol in order not to affect the measurements of anxiety
(Crome and Bloor, 2005).
No participant declared a psychiatric or another illness.
In order to ensure that the study group shows homogeneity
with respect to chronotype, morningness-eveningness questionnaire
of Horne and Östberg, 1976
was filled out and participants with similar characteristics
were included. This questionnaire establishes five behavioural
categories: definitively morning types (score=70-86), moderately
morning types (score=59-69), neither types (score=42-58),
moderately evening types (score=31-41) and definitively evening
types (score=16-30). The reliability of the Turkish version
of the Horne and Östberg questionnaire has been established
in a previous study (Punduk et al., 2005).
Moderately morning types (n = 6) and neither types (n = 7)
were included in this study.
Subjective sleep quality of participants was investigated
using Pittsburg Sleep Quality Index (PSQI) that is a self-noted
questionnaire that assesses sleep quality and sleep disturbance
over one- month period (Buysse et al., 1989).
It comprises 19 individual items generating seven "component"
scores: subjective sleep quality, sleep latency, sleep duration,
habitual sleep efficiency, sleep disturbances, use of sleeping
medication and daytime dysfunction. The sum of scores for
these seven components yields one PSQI global score. In addition
to showing global scores as a continuous variable, participants
were dichotomized into "good" sleepers (PSQI <
5) and "poor" sleepers (PSQI > 5) according to
previous methodology. We included good sleepers in our study.
PSQI scores of all participants were lower than 5 in our study
group. The mean (±SD) PSQI scores of participants were given
in Table 1. A Turkish
translation and reliability and validity studies of this scale
were performed in a Turkish sample (Agargun et al., 1996).
Study
design
The protocol included three parts: (1) baseline measurements,
(2) measurements following short-term total (30 hours) sleep
deprivation, (3) measurements following partial sleep deprivation
(Figure 1). With respect
to duration, total sleep deprivation may be divided into short-term
(< 45 hours) and long-term (> 45 hours) deprivation.
Partial sleep deprivation refers to sleep duration less than
5 hours per night (Pilcher and Huffcutt, 1996).
The first part of the study was performed in the next day
following the normal habitual sleep period. Following baseline
measurements, participants remained awake whole night and
day under the constant observation of two investigators in
our laboratory. During the sleep deprivation period, the participants
spent their time playing table games, reading books or watching
television. They were restricted from taking caffeine, tea
or other stimulants. The second Wingate Test was performed
for each participant at the same time period (14.00-16.00)
of the following day.
In the last section, all participants exposed to partial sleep
deprivation at least two weeks after total deprivation experiment.
They were observed by two investigators. The participants
were allowed to sleep between 03.00-07.00 am. They were taken
to the exercise laboratory at 08.00 am and kept awake until
the Wingate Test was performed. During this period, participants
were able to freely engage in a variety of activities (e.g.
play computer games, read books, watch television). State
anxiety scale and subjective sleepiness by visual analogue
scale (VAS) were recorded before each Wingate test. The participants
had isocaloric meals in lunch and dinner during the study
protocol in order to assure that meals eaten do not affect
sleep deprivation (Smith and Maben, 1993).
Anaerobic
test
The Wingate test consisted of a 30-second supramaximal cycling
against a resistance load. Each test was performed on a Monark
cycle ergometer (Model 894-E, Sweden) and for each participant
the load was calculated as 0.090 kg x.kg-1 body mass. The
participants warmed up by pedalling for 3 min against a 30
watt load. After 5 min rest period, by the command "start"
the participant began pedalling as fast as possible against
a predetermined work load until the end of the test period.
Strong verbal motivation was given to participants to maintain
maximal pedalling rate during the test. The data were used
to calculate peak power and mean power as reported by Bar-Or,
1987.
State-trait
anxiety scale (STAI)
The STAI was developed by Spielberger et al., 1970
to measure state and trait anxiety. Each participant's level
of anxiety was assessed using the STAI, which consists of
20 items, each representative of a category of anxiety symptoms.
Oner and LeCompte, 1985
determined the reliability and validity of the STAI for a
Turkish population. Participants completed state anxiety scale
before each Wingate test. Trait anxiety inventory was completed
only before the first anaerobic test.
Sleepiness
Subjective sleepiness was recorded using VAS. Participants
rated and reported how much sleepy they felt on a 100 mm horizontal
line from "very alert" on the left and "very
sleepy" on the right. Sleepiness score was measured as
the distance of mark from the left in millimetres.
Statistical
analysis
The state anxiety score was used as the basis to calculate
the power of this study. The power of this study was 85.6%
based on the maximum difference in the mean state anxiety
score =17.6 between levels, standard deviation=12.9, type
I error=5%, n=13.
General characteristics of the participants were presented
as mean ± standard deviations and range. Normality distribution
of variables was tested using Kolmogorov Smirnov test. The
effects of three different sleep conditions on anaerobic performance
and anxiety were evaluated by repeated measures analysis of
variance (ANOVA) test, and then Bonferroni post-hoc test was
used when the significance difference was obtained. Sleepiness
was evaluated by Freidman repeated measures ANOVA test due
to non-normal distribution, and then Bonferroni post-hoc test
was used when significant difference was obtained. P-value
<0.05 was considered statistically significant. Statistica
7.0 statistical software was used for statistical analyses.
|
| RESULTS |
|
Trait anxiety scores (33.11 ± 5.13) verified that our study group
was homogenous in terms of general anxiety level. Mean state
anxiety scores after total sleep deprivation were significantly
higher when compared to the baseline and partial sleep deprivation
measurements (Table 2).
VAS scores of total sleep deprivation day were significantly
higher than the baseline measurements (Table
2). No significant difference was observed between the
peak power, mean power and anaerobic fatigue values recorded
during Wingate Test after the baseline, total and partial
sleep deprivation nights (Table
2).
|
| DISCUSSION |
The main finding of this study is that anaerobic performance
parameters remained unchanged following 30 hours sleep deprivation,
although state anxiety levels of the participants were significantly
higher during the same period. In addition, one night of partial
sleep deprivation was not associated with enhanced anxiety or
impaired anaerobic performance. No statistically significant
alterations in anaerobic performance resulting from one night
of total or partial sleep loss were found.
Numerous studies have examined the relationship between anxiety
and performance (DeMoja and DeMoja, 1986;
Hogg, 1980;
Hume et al., 1993;
Jones and Hardy, 1988;
Kais and Raudsepp, 2004;
Parfitt et al., 1995;
Parfitt and Pates, 1999;
Pijpers et al., 2005).
Sleep deprivation was not evaluated as a factor that could affect
anxiety in studies focused on anxiety- performance relationship
whereas some studies demonstrated that sleep deprivation was
reported to produce anxiety in humans (Dinges et al., 1997;
Kahn-Greene et al., 2007;
Sagaspe et al., 2006).
In the present study, sleep deprivation was evaluated as an
anxiety inducer. The increase in anxiety levels was originally
due to total sleep deprivation rather than competition stress
or a pathological state.
It is questionable that whether these increased anxiety levels
were high enough to influence anaerobic performance parameters
(peak power, mean power and anaerobic fatigue). The peak power
represents the highest maximal voluntary contraction during
any 3- to 5- second period of the Wingate test. Peak power may
be affected from central (motivation) and peripheral (neuromuscular)
factors (Bernard et al., 1998).
Our study revealed that increased anxiety levels resulting from
total sleep deprivation do not appear to play any central or
peripheral effect in healthy participants.
In our study, the effect of sleep deprivation on anaerobic performance
was evaluated by using a supramaximal exercise test. It was
found that sleep deprivation did not affect anaerobic performance.
In previous studies, the effect of sleep deprivation on performance
was examined after treadmill walking at different levels of
VO2 max, and negative effects were reported (Martin,
1981;
Rodgers, 1995).
It seems that, there has been conflicting findings on the effect
of sleep deprivation on physical performance. One of the reasons
of this conflict may be examining the physical performance by
different standardised physiological tests. Another reason of
getting conflicting findings on the effect of sleep deprivation
on physical performance may be the duration of sleep deprivation.
In the present study, both total and partial sleep deprivation
were investigated in the same study population. Several studies
(Rodgers et al., 1995;
Symons et al., 1988;
Takeuchi et al., 1985)
investigated especially the effects of total sleep deprivation
on anaerobic performance. In general, no deterioration was revealed
in anaerobic performance following total sleep deprivation.
However, a recent study reported that 24 h sleep deprivation
unaffected but 36 h wakefulness decreased anaerobic performance
(Souissi et al., 2003). In a previous study, Mougin et al., 1996 investigated the effects of partial sleep deprivation
on the next day anaerobic performance in 8 highly trained athletes.
Their findings revealed that partial sleep deprivation does
not contribute to differences in various aspects of supramaximal
exercise including mean power and peak power. In the light of
above considerations, we suggest that short-term total or partial
sleep deprivation is not effective on anaerobic performance,
even though anxiety levels may be increased to some extent.
Anaerobic performance parameters could obtain specific information
for supramaximal exercise levels of individuals. We performed
only one test in a day and all tests were taken at the same
time period (14.00-16.00 p.m.) to prevent circadian variation
effects (time-of-day effect). Bernard et al., 1998 demonstrated the time-of-day effect in the
maximal anaerobic power of cycle test. They reported that there
were significant differences between the morning and the afternoon
measurements whereas no differences were observed between 14.00
and 18.00 hours. We preferred the same time period in order
to remove the time-of-day effect.
In this study anxiety and performance responses were obtained
in the laboratory environment. Performing the measurements in
laboratory provided us a more tightly controlled environment.
However, in terms of ecological validity, laboratory environment
may be disadvantageous as sportive environment is ever-changing
with its weather conditions and existence of other competitors.
A recent study revealed that sleep time was positively related
to vigor and inversely related to fatigue throughout an expedition
to the South Pole in winter (Pedlar et al. 2007).
Laboratory assessment isolates the participant from all these
ecological conditions. This may reduce the ecological validity
of this study.
There are several limitations of the study. First, we measured
state anxiety only once prior to anaerobic measurements. Continuous
monitorization of anxiety by certain intervals during whole
day would be beneficial. Secondly, our study includes subjective
anxiety evaluation; further studies are needed to demonstrate
objective self evaluations such as heart rate, blood pressure
and muscular tension to confirm our findings. Additionally,
our study population covered only male participants. Therefore,
extrapolation of these results to female athletes may lead to
misinterpretations.
Another confounding factor may be the order effect. All participants
were subjected to total sleep deprivation and then to partial
sleep deprivation. There were two weeks between these two deprivation
protocols. We think that an alternate model (first partial,
then total) would give the same results as two weeks period
is long enough for recovery. |
|
| CONCLUSION |
| In summary, many athletes can worry about the effects of inadequate
sleep on athletic performance in sports activities. We investigated
the effects of total and partial sleep deprivation induced anxiety
without any competition stress on anaerobic parameters. We showed
that only short-term total (30 hours) sleep deprivation but not partial
sleep deprivation may enhance anxiety in healthy participants. Finally,
we suggest that short-term total sleep deprivation may alter self
reported anxiety levels to some extent which seems to be ineffective
on anaerobic performance. |
| KEY
POINTS |
- Short time total sleep deprivation (30 hours) increases state
anxiety without any competition stress.
- Anaerobic performance parameters such as peak power, mean power
and minimum power may not show a distinctive difference from anaerobic
performance in a normal sleep day despite the high anxiety level
induced by short time sleep deprivation.
- Partial sleep deprivation does not affect anxiety level and anaerobic
performance of the next day.
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| AUTHORS
BIOGRAPHY |
Selma Arzu VARDAR
Employment: Ass. Prof., Department of Physiology, Trakya
University, Edirne, Turkey.
Degree: MD,PhD.
Research interests: The effect of exercise on sleeping,
the response of women to exercise.
E-mail: arzuvardar@trakya.edu.tr |
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Levent
ÖZTÜRK
Employment: Asc. Prof., Department of Physiology, Trakya
University, Edirne, Turkey.
Degree: MD.
Research interests: Sleep physiology, sleep and exercise
interactions, sleep related breathing disorders.
E-mail: leventozturk@trakya.edu.tr |
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Cem
KURT
Employment: Trakya University Physical Education and Sport
Department, Edirne, Turkey.
Degree: MSc.
Research interests: Plyometric exercise.
E-mail: cemkurt@hotmail.com |
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Erdogan
BULUT
Employment: PhD Student, Department of Physiology, Trakya
University, Edirne, Turkey.
Degree: MSc.
Research interests: Exercise induced changes in ouditory
brainstem evoked potantials.
E-mail: erbulut2004@yahoo.com |
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Necdet
SÜT
Employment: Ass. Prof., Trakya University, Department of
Bioistatistics Edirne, Turkey.
Degree: PhD.
Research interests: Multivariate statistical analysis,
application of neural networks and bayesian networks in medicine.
E-mail: necdetsut@yahoo.com
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Erdal
VARDAR
Employment: Asc. Prof., Trakya University, Faculty of Medicine,
Department of Psychiatry, Edirne, Turkey.
Degree: MD.
Research interests: Eating disorders, exercise psychology.
E-mail: erdalvardar@trakya.edu.tr |
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