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The effects of sleep deprivation on emotional empathy
VERONICA GUADAGNI
1
,FORDBURLES
1
, MICHELE FERRARA
2
and
GIUSEPPE IARIA
1
1
Department of Psychology and Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada and
2
Department of Life, Health and
Environmental Sciences, University of L’aquila, L’Aquila, Italy
Keywords
direct emotional empathy, sleep quality,
affective empathy, mirror neurones, mood,
social interaction
Correspondence
Veronica Guadagni, Department of Psychology,
A062, University of Calgary, Calgary, AB,
Canada, T2N 1N4.
Tel.: 403-220-3715;
fax: 403-282-8249;
e-mail: veronica@neurolab.ca
Accepted in revised form 5 June 2014; received
7 January 2014
DOI: 10.1111/jsr.12192
SUMMARY
Previous studies have shown that sleep loss has a detrimental effect on
the ability of the individuals to process emotional information. In this
study, we tested the hypothesis that this negative effect extends to the
ability of experiencing emotions while observing other individuals, i.e.
emotional empathy. To test this hypothesis, we assessed emotional
empathy in 37 healthy volunteers who were assigned randomly to one of
three experimental groups: one group was tested before and after a night
of total sleep deprivation (sleep deprivation group), a second group was
tested before and after a usual night of sleep spent at home (sleep group)
and the third group was tested twice during the same day (day group).
Emotional empathy was assessed by using two parallel versions of a
computerized test measuring direct (i.e. explicit evaluation of empathic
concern) and indirect (i.e. the observer’s reported physiological arousal)
emotional empathy. The results revealed that the post measurements of
both direct and indirect emotional empathy of participants in the sleep
deprivation group were significantly lower than those of the sleep and
day groups; post measurement scores of participants in the day and
sleep groups did not differ significantly for either direct or indirect
emotional empathy. These data are consistent with previous studies
showing the negative effect of sleep deprivation on the processing of
emotional information, and extend these effects to emotional empathy.
The findings reported in our study are relevant to healthy individuals with
poor sleep habits, as well as clinical populations suffering from sleep
disturbances.
INTRODUCTION
Sleep is important for our mental, physical and emotional
wellbeing. It plays a critical role in a variety of functions,
including restoration of the endocrine and metabolic pro-
cesses (Spiegel et al., 1999), energy conservation (Moor-
croft, 2013), memory consolidation (Diekelmann and Born,
2010) and recovery of cortical functioning (Drummond et al.,
1999). In support of such a critical role, it has long been
established that sleep deprivation degrades several aspects
of neurocognitive performance: it reduces learning capacity,
impedes divergent thinking, increases ineffective response
perseveration (Durmer and Dinges, 2005), increases atten-
tion lapses and reaction time (Lim and Dinges, 2010) and
decreases hand–eye coordination (Elmenhorst et al., 2009).
Although cognitive tasks vary considerably in their sensitivity
to sleep loss, to date the fundamental role of sleep on the
proper functioning of our daily life is widely accepted (Durmer
and Dinges, 2005).
Sleep deprivation appears to have the largest adverse
effects on performance when the executed tasks depend
upon the functional integrity of the prefrontal cortex (PFC)
(Couyoumdjian et al., 2010; Drummond et al., 2006; Harrison
et al., 2007; Killgore et al., 2006). The PFC is well known to
be involved in executive functions (Yuan and Raz, 2014), as
well as in the regulation of emotions, and particularly in the
ability to shift to someone else’s perspective (Ochsner,
2013). Accordingly, sleep deprivation has been shown to
greatly influence the ability to process emotional information
(Kahn et al., 2013), and its negative effects on mood seem to
be more prominent than its effects on cognitive and motor
performance (Pilcher and Huffcutt, 1996). More specifically,
sleep loss seems to increase the propensity of the individuals
to experience negative emotions (Babson and Feldner, 2010)
ª2014 European Sleep Research Society 657
J Sleep Res. (2014) 23, 657–663 Empathy and sleep
and decrease their capacity to recognize emotions from facial
expressions (Minkel et al., 2010). Sleep deprivation also
alters pitch and vocal energy of spoken word (McGlinchey
et al., 2011), as well as sympathetic responses (e.g. pupillary
dilation) triggered by negative stimuli (Franzen et al., 2009).
In addition, recent studies have shown that sleep loss affects
the ability to recognize and categorize other people’s
emotions (Tempesta et al., 2010; Van Der Helm et al.,
2010), and reduces the individual’s self-perceived emotional
intelligence by affecting the ability to be empathetic towards
others (Killgore et al., 2008), which may result in a higher
number of conflicts following a poor night of sleep in young
couples (Gordon and Chen, 2013). Altogether, these studies
provide clear evidence that sleep deprivation is detrimental to
mood and emotion processing in general (Kahn et al., 2013)
and may have significant negative effects on some more
complex emotion processes, such as those involved in
empathy.
Empathy refers to the ability of an individual to understand
another person’s mental state in terms of emotions, feelings
and thoughts, which is important for an effective interpersonal
interaction (Shamay-Tsoory, 2011). Recently, the general
concept of empathy has been conceptualized into two
different components, i.e. cognitive and emotional empathy
(Dziobek et al., 2008; Shamay-Tsoory, 2011; Shamay-Tso-
ory et al., 2009). Cognitive empathy (also referred to as
theory of mind) refers to the individual’s ability to understand
another person’s perspective, feelings and state of mind
(Baron-Cohen, 2004). It underpins the ability to predict
others’behaviour, to manipulate or deceive people to our
own advantage, and to understand when individuals are lying
or holding a false belief. Conversely, emotional empathy
refers to the ability to understand the emotions of others by
vicariously sharing them (Smith, 2006). It can manifest as
increased feelings of distress while observing someone else
in a negative situation, and does not require an explicit
understanding of why the individual is suffering (Rankin
et al., 2005). Recently, Dziobek and colleagues (Dziobek
et al., 2008) further divided emotional empathy into direct and
indirect components. The direct emotional empathy compo-
nent refers to the explicit evaluation of the observer’s feelings
while attending someone else in an emotional situation (e.g. I
am concerned/angry that this person is being harmed).
Indirect emotional empathy refers to the physiological arousal
of the observer while attending someone else in an emotional
situation (e.g. my heart is racing/I felt an adrenaline rush
when I saw a person being harmed).
This recent bi-dimensional conceptualization of empathy
into cognitive and emotional components has theoretically
evolved from a more traditional measurement of empathy, as
developed by Davis in 1980 (Davis, 1980). In his Interper-
sonal Reactivity Index (IRI) questionnaire, Davis highlights
four different aspects of empathy: (1) perspective-taking,
which is defined as the individual’s spontaneous attempt to
take the perspective of others; (2) fantasy, which refers to the
ability of individuals to identify themselves with characters
encountered in movies and books; (3) empathic concern,
defined as the feelings of concern and compassion that
individuals may experience for others; and (4) personal
distress, which refers to the negative feeling of anxiety and
distress that people undergo while observing someone in a
negative situation. Within the most recent categorization of
empathy, Davis’dimensions of perspective-taking and fan-
tasy are conceptualized as cognitive empathy and empathic
concern and personal distress as emotional empathy (Kaplan
and Iacoboni, 2006).
To date, although an increasing number of studies
suggests that sleep loss may be indeed detrimental to some
aspects of empathy (Gordon and Chen, 2013; Killgore et al.,
2008; Tempesta et al., 2010; Van Der Helm et al., 2010), the
effect of sleep loss on emotional empathy has been never
specifically probed. In this study, we adopted the emotional
empathy test developed by Dziobek et al. (2008) to test the
specific hypothesis that sleep deprivation results in a reduced
emotional empathic response, compared to the measures
obtained from the same individuals before the night of sleep
loss and the measures obtained in a different group of
individuals who underwent a usual night of sleep.
METHODS
Participants
We recruited 37 healthy volunteers [15 males and 22
females, mean age = 22.05, SD = 4.08 years, mean
education = 15.47, SD = 2.43 years]. At the time of testing,
none of the participants were taking any psychoactive
medication, nor had a history of medical, neurological or
psychiatric disorder. The study was approved by the
local research ethics board and participants were
required to provide informed consent before the experiment
began.
Groups
Participants were assigned randomly to one of three different
groups: the sleep deprivation group (n= 13), the sleep group
(n= 12) and the day group (n= 12). Participants in all
groups were tested twice. Subjects in the sleep deprivation
group were tested at 9 pm, before a night of total sleep
deprivation, and 8 am on the following morning. The sleep
deprivation night occurred in the laboratory where partici-
pants were monitored by two experimenters. The laboratory
had no windows and was constantly illuminated by full-
spectrum fluorescent lamps. Throughout the night of sleep
deprivation, subjects were allowed to perform activities such
walking, surfing the internet, watching movies and playing
board games. Lying down, sleeping and engaging in vigorous
physical activities were not permitted. They were allowed to
consume snacks and caffeine-free soft drinks; caffeinated
drinks, large amounts of chocolate and sweets, alcohol and
psychoactive medications were not allowed. Cigarettes were
ª2014 European Sleep Research Society
658 V. Guadagni et al.
limited to three for the entire duration of the study. Subjects in
the sleep group were tested at 6 pm and 10 am on the
morning following a usual night of sleep. Participants in this
group spent a night of undisturbed sleep at home and
provided a sleep log to ensure that their quality of sleep was
adequate. The time slept during the experimental night
(mean = 6:38, SD = 1:38) was not significantly different from
the average sleep duration (mean = 7:40, SD = 1:50)
reported for the month preceding the study (t
11
=1.672,
P= 0.48). Finally, participants in the day group performed
the pre and post sessions of the study during the same day at
10 am and 6 pm, respectively; this group served as a control
for the passage of time and fatigue. The experimental groups
did not differ in the average sleep duration reported for the
month preceding the study (F
2,34
= 1.570, P= 0.22).
Questionnaires
Before performing the experimental tasks, we asked partic-
ipants to complete the State–Trait Anxiety Inventory (STAI;
Spielberger et al., 1970) in both STAI Y-1 (State) and STAI
Y-2 (Trait) forms, to control for abnormal anxiety (scores >
48). We also asked participants to complete the Beck
Depression Scale (Beck et al., 1961) to check for the
presence of abnormal depressive traits (scores > 17), and
the Online Alexithymia Questionnaire (OAQ-G2) (Paula-
Perez et al., 2010) to ensure that participants were not
alexithymic (scores > 113), a condition characterized by
difficulty in distinguishing and appreciating the emotions of
others. In addition, we asked participants to complete the IRI
(Davis, 1980). Each participant’s quality of sleep was
assessed by the Pittsburgh Sleep Quality Index (PSQI;
Buysse et al., 1989), which evaluated sleep quality through-
out the month preceding the study; this scale confirmed
that all participants included in our study had a fair quality of
sleep (PSQI score mean = 5.38, SD = 2.12), with an
average sleep onset time of 12:12 am (SD = 1:19) and an
average sleep duration of 7 h 6 min (SD = 1:11). No
instances of sleep during the day occurred in any of the
participants.
Experimental tasks
The experimental tasks consisted of a modified version of the
Multifaceted Empathy Test (MET) (Dziobek et al., 2008),
which is used to assess direct and indirect emotional
empathy. Our experimental tasks were created by using
120 coloured images selected from the International Affective
Picture System (IAPS) (Lang and Bradley, 2007). An equal
number of images depicted people in positive (valence mean
= 8.0; arousal mean = 5.1), neutral (valence mean = 5.0;
arousal mean = 3.6) and negative (valence mean = 2.0;
arousal mean = 6.0) scenes, as categorized by the IAPS
normative data. We selected only pictures that included
people and in which emotional expressions were clearly
visible. We used this set of images to create two parallel
versions of the same task, the administration order of which
was balanced across testing sessions. The two tasks
consisted of 60 images each, matched for image valence
and arousal, as provided by the IAPS normative data.
In each task, the 60 images were presented three times,
each time paired with a specific question that aimed to
measure either direct emotional empathy (i.e. ‘how strong is
the emotion you feel about this person?’), indirect emotional
empathy (i.e. ‘how calm/aroused does this picture make you
feel?’) or a mere image valence judgement (i.e. ‘how would
you judge this image?’positive/negative/neutral). The image
valence query was included to ensure that the participants’
image judgements were consistent with the normative ratings
provided by the IAPS. Therefore, each task consisted of 180
trials. In each trial, participants were shown an image and
asked to answer one of the three questions described above
as quick as possible, using the keyboard. Participants
responded to the direct and indirect emotional empathy
questions by using a reduced version of the Self-Assessment
Manikin (SAM) valence scale. The SAM valence scale
(Bradley and Lang, 1994) is a cartoon-type figure in which
nine human emotional expressions, ranging from calm and
not concerned to anxious and very concerned, are repre-
sented. In our study we utilized a reduced version consisting
of four figures that captured the entire range of the full
version. Participants were required to answer the three
questions on randomized blocks of 10 trials each. Each task
included 18 blocks, and each block only had one question
posed. Each block was initiated with an on-screen query for
the duration of 4000 ms, followed by a fixation cross (range
1000–3000 ms, mean = 2000 ms, within each block) and the
image stimulus, which remained on-screen until participants
responded, or until 10 s had elapsed. In each experimental
task the presentation of the blocks was randomized, and the
task began with a practice session consisting of six trials.
Fig. 1 contains samples of trials used in the tasks.
Data analysis
First, a Pearson’sv
2
test was performed between IAPS
normative image valence and participants’image valence
ratings, to ensure that these ratings were consistent. Then,
we performed a correlation analysis between the subscales
of the IRI and our tasks for both direct and indirect emotional
empathy to evaluate the relationship between these two
different measures of empathy. Finally, although there were
no pre-existing differences in the direct (F
2,33
= 1.168,
P= 0.32) and the indirect (F
2,33
= 0.731, P= 0.48) emotional
empathy scores between groups, we ran a series of analyses
of covariance (ANCOVAs) in order to assess the effects of sleep
deprivation on both components of emotional empathy. Pre
session scores were used in the ANCOVA as covariates, and
the scores on the post session were used as the dependent
variable. This approach was chosen because of the strong
correlation between the pre- and postscores for both direct
(r
34
= 0.861, P< 0.01) and indirect (r
34
= 0.870, P< 0.01)
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Sleep and emotional empathy 659
emotional empathy, which makes ANCOVAs more powerful
than a mixed analysis of variance (Tu and Gilthorpe, 2011).
Groups were compared pairwise. For all analyses, we set a
two-tailed level of significance at P= 0.05 unless noted
otherwise.
RESULTS
Upon an initial overview of the data, one participant from the
day group was excluded from further analyses due to
extreme changes in responses from pre- to post session on
both direct and indirect emotional empathy (Z= 4.11 and
8.36, respectively). Pearson’sv
2
analysis revealed that
image affect ratings provided by the participants in the pre
session were consistent with IAPS ratings (average v
2
=
5.539, P
right-tailed
= 0.06).
The correlation analyses between the IRI and our empa-
thy tasks revealed that pre session scores for both direct
(r
34
= 0.334, P= 0.05) and indirect (r
34
= 0.339, P= 0.04)
emotional empathy were correlated with the perspective-
taking subscale of the IRI. The correlations between
the other subscales of the IRI and both direct and indirect
emotional empathy were not significant (fantasy: r
34
=
–0.002, P= 0.99 and r
34
= 0.059, P= 0.73; empathic
concern: r
34
= 0.236, P= 0.17 and r
34
= 0.220, P= 0.20;
and personal distress: r
34
= 0.082, P= 0.63 and r
34
= 0.151,
P= 0.38, respectively).
To assess the effects of sleep deprivation on direct and
indirect emotional empathy, participants’pre scores were
used as covariates when comparing post scores between
groups (see Methods). After testing gender as a predictor in
each analysis and finding no significant differences, we
Figure 1. The figure depicts the sample of a trial assessing the ability of participants to recognize the image valence (left column), emotional
empathy indirect (centre column) and emotional empathy direct (right column).
ª2014 European Sleep Research Society
660 V. Guadagni et al.
removed the gender factor from further analyses. The
ANCOVAs revealed that the indirect emotional empathy post-
scores of participants in the sleep deprivation group (mean
=1.99, SD = 0.40) were significantly lower than scores of
participants in both the day (mean = 2.37, SD = 0.41) (F
1,21
=
6.921, P= 0.01) and sleep (mean = 2.25, SD = 0.32) (F
1,22
=
4.467, P= 0.04) groups; post scores of participants in the
day and sleep groups did not differ significantly (F
1,20
=
0.447, P= 0.51). Similar results were found in the context of
the direct emotional empathy, showing that post scores of
participants in the sleep deprivation group (mean = 1.94, SD
= 0.37) were significantly lower than scores of participants in
both the day (mean = 2.45, SD = 0.49) (F
1,21
= 12.150,
P= 0.00) and sleep (mean = 2.26, SD = 0.35) (F
1,22
= 4.869,
P= 0.03) groups; post scores of participants in the day and
sleep groups did not differ significantly (F
1,20
= 1.424,
P= 0.24). Changes in scores from the pre- to the post
session in all groups are shown in Fig. 2. As expected, the
ANCOVAs performed on participants’image valence ratings
revealed that post scores of participants in the seep depri-
vation group did not differ significantly from the post scores of
participants in the day (F
1, 21
= 1.512, P= 0.23) and sleep
(F
1,22
= 1.637, P= 0.21) groups.
DISCUSSION
In this study we tested the hypothesis that a night of total
sleep deprivation has a detrimental effect on the capacity of
the individuals to share other’s emotions (i.e. emotional
empathy). The results revealed that after a night of sleep
deprivation participants were less emotionally empathetic
than those who had slept, as well as those participants
retested during the same day. The effects were similar for
both direct and indirect components of emotional empathy.
Our results indicate that a night of sleep loss impairs the
ability to share the emotional state of others, which is an
important skill in everyday social interactions in both the
workplace and personal life. These findings are consistent
with previous research revealing negative effects of sleep
loss on cognition and emotional processing in general, and
extend these effects to emotional empathy in particular.
Previous research has demonstrated how sleep loss may
have a negative impact on the individual’s ability to be
empathetic towards others. In a recent study, Van der Helm
and colleagues (Van Der Helm et al., 2010) tested 37
healthy participants, assigning them randomly to the sleep
control or total sleep deprivation groups. Participants
performed an emotional face recognition task in which they
were asked to evaluate the emotion shown by a subject in a
photograph as sad, happy or angry. The findings revealed
that sleep deprivation selectively impairs the judgement of
facial emotions, particularly those threat-relevant (angry)
and reward-relevant (happy). The authors argued for the
susceptibility of the prefrontal lobe to sleep deprivation as
an explanation for their results. This interpretation is in line
with a recent neuroimaging study by Yoo et al. (Yoo et al.,
2007) showing that, during an emotional viewing task,
hyperactivity in the amygdala can be detected due to a lack
of inhibitory control from the medial prefrontal cortex
(MPFC), as affected by sleep loss. In a different study,
Gordon and Chen (2013) examined the effect of poor-quality
sleep on conflict resolution in 78 individuals involved in a
romantic relationship. The authors reported an increased
number of conflicts following nights of poor sleep across the
14 days of the study. Moreover, poor sleep was associated
with a lower ratio of positive to negative affect as well as
decreased empathic accuracy while asking about partner’s
emotions during a conflict conversation. Altogether, the
aforementioned studies provide evidence that sleep loss
has a significant negative effect on some aspects of human
empathy. Our study provides complementary evidence to
the existing literature, extending previous findings to the
concept of emotional empathy, by showing that sleep
deprivation reduces the specific ability to share emotions
experienced by others.
With regard to the measures of empathy as used in our
study, our findings revealed a significant correlation
between our direct (r
34
= 0.334, P= 0.05) and indirect
(r
34
= 0.340, P= 0.04) emotional empathy and the per-
spective-taking subscale of the IRI. This relationship may
be explained by the role of the mirror neurone system
(MNS) in emotional empathy. The MNS is comprised
Figure 2. Experimental groups’postscores on measures of direct and indirect emotional empathy. Significant differences are marked with an
asterisk. n= 36; error bars represent 1 standard deviation.
ª2014 European Sleep Research Society
Sleep and emotional empathy 661
primarily of the inferior frontal gyrus (IFG; BA 44–46) and
inferior parietal lobule (IPL; BA 39–40) (Rizzolatti and
Craighero, 2004). In humans, it has been shown that the
MNS is active not only while observing someone else’s
actions but also when attending to their emotional state. In
fact, recent studies have shown that mirror neurones,
together with regions of the limbic system such as the
amygdala and the insula, are involved in emotion recogni-
tion and evaluation (Carr et al., 2003), as well as in the
processing of emotional empathy (Jabbi et al., 2007).
Patients with lesions in the IFG, particularly BA 44, show
deficits in emotion recognition and emotional empathy
(Shamay-Tsoory et al., 2009), but not in second-order
false-belief tasks. This suggests that the IFG plays a key
role in the ability to relate emotionally to another individual.
Interestingly, the MNS is reported to be more active in
individuals with high scores on the perspective-taking
subscale of the IRI (Gazzola et al., 2006). Therefore, it is
possible that the correlation between scores on the
perspective-taking subscale of the IRI and direct and
indirect emotional empathy tasks may be due to the MNS
as a common neural substrate for both processes in young,
healthy participants. Further research is required in order to
test this hypothesis.
Future neuroimaging studies may test the hypothesis that
reduced empathic responses (as an effect of sleep depri-
vation) may be related to functional and structural proper-
ties of selective neural mechanisms responsible for
empathy. In fact, sleep deprivation has been shown to
affect the resting state functional connectivity between a
variety of brain areas including the thalamus, posterior
cingulate cortex, anterior cingulate cortex, ventromedial
prefrontal cortex and amygdala (Chee, 2013). In addition
to changes in resting state connectivity, sleep loss has also
been shown to alter task-related neural activity in the IFG
(Habeck et al., 2004). These findings seem to support the
hypothesis that sleep deprivation may affect the functional
proprieties and connectivity of the neural networks that are
known to be critical for emotional empathy, which includes
the IFG and the IPL, together with regions of the limbic
system such as the insula and the amygdala. Future
neuroimaging studies may be able to test this important
hypothesis and shed more light on the neurological effects
of sleep loss.
ACKNOWLEDGEMENTS
We would like to thank our participants for contributing to this
study, especially those individuals included in the sleep
deprivation group.
CONFLICT OF INTEREST
The authors declare the absence of financial support and off-
label or investigational use, and the absence of any conflicts
of interest.
AUTHOR CONTRIBUTIONS
VG conceived the study, performed data collection and
analyses and wrote the manuscript. FB participated in data
analyses and interpretation and assisted in drafting the
manuscript. MF and GI contributed in conceiving the study,
providing data interpretation and writing the manuscript.
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