Table of Contents
Definition and Morbidity of Night Eating Syndrome
Comorbidities and Differential Diagnosis
Energy Intake Timing Pattern in NES
Treatment of Night Eating
Albert J. Stunkard Speaks Out About Night Eating Syndrome
by Sandra Haas Binford, MAEd
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Thanksgiving weekend in America, a national holiday when everyone thinks about
eating, is an appropriate time to interview Dr. Albert Stunkard to discuss people who
eat too many calories at the wrong time of day. Is such behavior an American
phenomenon or the result of an underlying problem? Considering the problem of
excessive calorie-consumption regardless of timing, the American obesity epidemic
requires that clinicians and the public learn more about night eating syndrome.
Stunkard Albert J. Stunkard, MD, Emeritus Professor and former Chair of Psychiatry at the
University of Pennsylvania School of Medicine, is a pioneer in the psychiatry of eating
disorders, being first to describe the powerful influence of social class on obesity, first to describe
both binge eating and night eating syndromes, and author of a widely used questionnaire to assess
the psychological aspects of eating behavior.(1) His awards include the Institute of Medicine's
Rhoda and Bernard Sarnat International Prize(2) and the Academy of Eating Disorders Lifetime
Achievement Award;(3) the Obesity Society named an award in his honor, the Mickey Stunkard
Lifetime Achievement Award.(4) Yet, he says that his contribution is "reasonable but not
In our conversation on November 27, 2010, Dr. Stunkard
said, "My research into night eating syndrome is one of the
few distinctive things I have contributed." Dr. Stunkard is
eager to teach others about night eating syndrome, and his
great concern that night eating syndrome remains
underdiagnosed deserves our close attention.
Definition and Morbidity of Night
Eating Syndrome Ms. Binford and Dr. Stunkard
"I first reported it in 1955 in an 18-year-old obese woman
who was overeating and gaining weight,"(5) says Dr. Stunkard. He casually characterizes night
eating syndrome (NES) as eating a "negligible breakfast" and consuming 25% of total, daily caloric
intake after the evening meal. He adds that specifying 25% of total daily calories may be rather
conservative, so some investigators have used percentages as high as 50%.(6,7) One of his more
formal definitions describes NES as consisting of "morning anorexia, evening hyperphagia, and
insomnia,"(8) and the evolved, operationalized definition as of 2005 was "engaging in evening
hyperphagia (consumption of ≥ 25% of total daily calories after completion of the evening meal)
and/or nocturnal awakenings accompanied by ingestions of food (≥ 3 episodes/week)."(9) In fact,
as we will see below, the waking component may be key to understanding the etiology, diagnosis,
and treatment of NES.
Although NES is a clinically recognizable syndrome, it is described only under Eating Disorder Not
Otherwise Specified (EDNOS) in the Diagnostic and Statistical Manual, Fourth Edition, Text Revision
(DSM-IV-TR) of the American Psychiatric Association.(10) When asked about the likelihood of it
being included as a "disorder" in the Diagnostic and Statistical Manual, Fifth Edition (DSM-5),
where it is not in the published draft,(11) he says that his new and upcoming papers "might help."
He adds that the American Psychiatric Association is "concerned that there are too many new
diagnoses in DSM-5." His research team has recently proposed diagnostic criteria for NES(12) and
he thinks it probable that NES will be included as a separate disorder in DSM-5.
Dr. Stunkard says of night eating that "wider recognition is needed" among physicians.
Approximately 3.5% of women and 4.5% of men in the United States experience night eating
behavior as defined above. Indeed, across many countries and continents, its prevalence is
estimated at 4% to 5% of the population. Further, this behavior tends to be associated with
obesity, an epidemic of increasing proportion in the United States population. In their original
description of 1955, Dr. Stunkard and colleagues noted a 64% prevalence of NES among difficult-
to-treat obese patients. More recent papers document that NES is common among clinically obese
patients, with prevalences of 6% among those with a body mass index (BMI) > 35;(13) of 16%
among 166 obese subjects in an Italian study;(14) and of 27% among patients who had undergone
gastric restriction surgery;(15) among others. Because nonobese persons (BMI < 25) show similar
responses on the Night Eating Questionnaire(16) to those of obese persons (BMI > 30), but are
notably younger, Dr. Stunkard and his colleagues proposed in a 2004 paper that NES may
contribute to the development of obesity.(17)
Many patients have sought treatment, but all too often, psychiatrists and other physicians are not
recognizing the symptoms as those of night eating syndrome. "Almost none of the obese NES
patients who came to me because of their obesity had had their NES recognized and they had
usually been looking for help for over a year," he elaborates.
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Comorbidities and Differential Diagnosis
Night eating syndrome is not to be confused with "sleep-related eating disorder" (SRED), in which
one eats while sleeping. In contrast, patients with NES awaken before eating, clarifies Dr.
Stunkard. Further distinction between these syndromes is published elsewhere in the literature.
Sleep-related eating disorder is also characterized by compulsive binge eating during diurnal
awakenings, but exhibits night eating behaviors linked with reduced consciousness and sleep
disorders, mainly somnambulism. Sleep-related eating disorder seems to be a clinical subtype of
sleep disorders,(6) not an eating disorder, as NES is.
NES is also distinguished from binge eating disorder; the two conditions can be comorbid, but are
different. As discussed in the recent Compass Points™ article on eating disorders (August 9,
2010),(18) binge eating disorder is characterized by the binge eating behavior seen in bulimia but
without the subsequent attempts at weight loss,(19) particularly by vomiting, Dr. Stunkard adds.
Bingeing involves taking in an unusually large quantity of food in a discrete time period and feeling
a sense of lack of control during the episode.(10) Dr. Stunkard maintains that it is much more
difficult to treat comorbid binge eating and night eating than either condition alone.
In a study of major depressive disorder (MDD) and night eating syndrome, Dr. Stunkard and
colleagues published results in 2009 of serotonin transporter (SERT) binding affinity using single-
photon-emission computed tomography in patients with MDD and NES. This study demonstrated
that patients with NES had significantly greater SERT uptake ratios in the midbrain, right temporal
lobe, and left temporal lobe regions than those with MDD, suggesting that these are distinct clinical
Other researchers have published evidence that NES and winter seasonal affective disorder (SAD)
are not overlapping syndromes, although they share some features, including snacking with high-
carbohydrate/high-fat food with increased weight, emotional distress, circadian disturbances, good
response to serotonergic antidepressants (SSRIs), and bright-light therapy.(21)
Some patients feel a strong desire to eat in NES, but there is no evidence that night eating
behaviors in NES represent obsessive compulsive disorder (OCD), Dr. Stunkard says.
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Energy Intake Timing Pattern in NES
In 1999, Dr. Stunkard and Norwegian colleagues published findings of two arms of research into
the behavioral and neuroendocrine characteristics of NES. Although NES was empirically described
in 1955, this later research showed through careful clinical study that night eaters experienced
more than double the number of eating episodes in each 24 hours and consumed significantly more
of their daily energy intake at night than did control subjects. They also awoke many more times
per night, consumed food more than half of the times they awakened, and showed lower nocturnal
levels of melatonin and leptin. Peak levels of the stress hormone cortisol were higher than those of
Dr. Stunkard says that the "need to eat is probably on a circadian rhythm." In 2004, he and his
colleagues published findings indicating no difference between the total energy intake of the
subjects with NES and the control subjects, but the timing pattern of energy intake differed greatly
between these groups. Although subjects with NES had sleep onset, offset, and total sleep duration
times comparable with those of controls, they reported more nighttime awakenings than did
controls. Further, actigraphic monitoring showed that patients with NES awakened a mere 128
minutes after sleep onset, while control subjects first roused, on average, 193 minutes after onset
of sleep. Subjects with NES consumed food on 74% of the awakenings, whereas no control
subjects ate. The study concluded that NES may involve a dissociation of the circadian control of
eating relative to sleep.(23) In 2009, his team published findings that phase delays of 1.0 hours –
2.8 hours were found in the 2 food-regulatory rhythms of leptin and insulin, as well as in the
circadian rhythm of melatonin (with a trend for a delay in the circadian cortisol rhythm).(24)
Further, Dr. Stunkard shares the "fairly new" finding that, in a 24-hour cycle, the circadian rhythm
is delayed by 1 – 2 hours in patients with NES. Ray Boston, PhD, MSc, at the University of
Pennsylvania School of Veterinary Medicine, performed the calculations in this study, which is still
People with NES do not feel out of control, but they do feel guilty about night eating. When they
are "bogged down in guilt, they overeat and feel depressed overall, especially at night, after
eating." They also exhibit rational, then irrational, thinking with regard to their nighttime eating
behavior, for example:
Rational thinking: "'If I eat, maybe I'll be able to sleep more.'"
Irrational thinking: "If I don't get to sleep, 'curses—that's because I ate something.'"
NES is believed to be characterized by a lack of serotonin in the neurons that control eating in the
satiety center, Dr. Stunkard adds.
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Treatment of Night Eating
While Dr. Stunkard's 1992 writing states that "attempts at weight reduction in the presence of
[NES is] inordinately difficult and may subject the patient to unnecessary distress,"(8) he now
describes a pharmacological treatment that helps patients lose weight, one that he calls "so
simple." He also names cognitive behavioral therapy as a potentially useful monotherapy or
adjunct to support pharmacotherapy.
"We've used ... selective serotonin reuptake inhibitors (SSRIs) that restore normal circadian
rhythm and neuroendocrine levels. When the rhythm is shifted back to normal, it is easier for
patients to lose weight. It's gratifying that medication helps them." Dr. Stunkard states that he
uses the same dosage of SSRIs as recommended for the treatment of major depressive disorder.
[Author's note: These agents are not FDA-approved for the treatment of night eating syndrome.]
This use of an SSRI was first reported in 2004 in a clinical trial of sertraline in the treatment of
night eating syndrome.(26) In a later, randomized, placebo-controlled trial of sertraline, twelve
subjects in the sertraline group (71%) were classified as having responded with a "much or very
much improved" in the Clinical Global Impression (CGI)(27) rating of at least 2, whereas only three
subjects (18%) in the placebo group showed such response. There were also significant
improvements in night eating symptoms, CGI severity ratings, quality-of-life ratings, frequency of
nocturnal ingestions and awakenings, and caloric intake after the evening meal. Overweight and
obese subjects in the treatment group lost a significant amount of weight by week 8.(28) This
treatment was further tested through a telemedicine paradigm, in which SSRI pharmacotherapy
obtained results similar to those reported earlier and facilitated specialty consultation to personal
physicians of 50 study participants.(29)
Here lies the crux of the problem: "Doctors do not know what to do with NES. They figure, if they
can help their patients sleep, then the patients will not be awake and eating during the night. The
former practice of giving hypnotics or sleeping pills has fallen out of favor. However, while these
agents were in use, instead of helping, they might have caused patients to become disorganized
and eat even more." Dr. Stunkard states, "When doctors treat with hypnotics, it doesn't help and it
may make the condition worse. NES responds well to SSRIs," as noted above.(26,28,29)
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Cognitive-behavioral therapy (CBT) has demonstrated promising results and should be explored
further through a controlled treatment trial. The 2010 pilot study into CBT for night eating showed
significant improvements in the core aspects of NES and weight reduction. Specifically, the pilot
study showed significant decreases in caloric intake after dinner, number of nocturnal ingestions,
weight, and score on the Night Eating Symptom Scale(30) and the Night Eating Questionnaire.(16)
Therefore, CBT may be sufficient treatment of NES in its own right, but further studies are needed.
Dr. Stunkard states, "Patients often feel so 'down in the dumps' that even with SSRI treatment,
they still worry whether the freedom from NES will remain stable." This worry may occur even
when they have only a thought of night eating but do not follow through with the behavior. "CBT
encourages patients to have faith in themselves that they are not at the mercy of impulses."
Further, "it helps to talk to them to improve optimism that treatment works."
When asked about other nonpharmacological therapy for NES, Dr. Stunkard immediately
mentioned investigations into changing lighting, although this treatment is "still in its infancy." In
the 2009 paper on circadian rhythm profiles in NES, his team proposed that NES may result from
dissociations between central (suprachiasmatic nucleus) timing mechanisms and putative
oscillators elsewhere in the central nervous system or periphery, such as in the stomach or liver.
The authors suggest that bright-light therapy may be useful as a chronobiologic treatment for
NES—noting that it has shown efficacy in reducing night eating in case studies—and that it should
be evaluated in controlled clinical trials.(24)
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Dr. Stunkard describes his team's latest, unpublished finding that, in a 24-hour cycle, the circadian
rhythm is delayed by 1 – 2 hours in patients with NES. Clinicians who carefully question their
patients about sleeping and eating habits during the night are most likely to recognize night eating
syndrome. He recommends asking these three questions:
1. "What time do you usually get to sleep?"
2. "If you wake up after you are asleep, how easy is it to fall asleep again?"
3. "Does eating make it easier to get back to sleep?"
The most helpful future research into night eating syndrome would be would be to find a new gene
for it. The challenge is the expense of such a project: The necessary "genome-wide association
study" would require 1,000 – 3,000 research subjects. Dr. Stunkard, a researcher whose early and
continuing twin and adoption studies(7,31) made history in distinguishing the environmental and
genetic influences on obesity, would see his work on night eating syndrome come full circle through
Dr. Stunkard concludes, "There is a disorder and it is easy to recognize and to treat—but it is not
widely recognized." He predicts that night eating syndrome will become more widely known once
doctors know that it can be treated.
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1. Knowledge: The clinician should improve recognition of night eating syndrome (NES) as a
serious medical problem and one that is common among obese persons.
2. Competence: The clinician should assess night eating syndrome as a circadian rhythm
3. Performance: The clinician should:
a. Take a careful, detailed eating history and intake assessment that includes
nighttime habits, asking the three questions noted above. "It makes the syndrome
more obvious if the patient is waking up to eat."
b. Consider treatment with a selective serotonin reuptake inhibitor (SSRI) based on
current evidence for treating NES,(26,27,29) instead of prescribing a sleeping aid.
[Author's note: These agents are not FDA-approved for the treatment of night
4. Patient Outcomes: The patient must have clinical follow-up and understand the purpose of
treatment. Cognitive behavioral therapy may be sufficient treatment by itself and may
improve results of other treatment. Appropriately treated patients should experience
resolution of their night eating behavior.
Penultimate draft version reviewed by Albert J. Stunkard, MD, on December 21, 2010.
Acknowledgements: The author gratefully acknowledges the time and contributions of Albert J.
Stunkard, MD, to this article.
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Your responses to this issue's Compass Questions™ will be added to an ongoing needs assessment
for educational programming in this important area. Responses to this issue's questions will be
reported in an upcoming issue.
NOW that you have read this article, how often WILL you screen for night eating syndrome among
overweight and obese patients with symptoms of waking up to eat in the night?
N/A - This is not my role
NOW that you have read this article, how often WILL you diagnose behaviors of night eating
syndrome in the context of the DSM-IV-TR under Eating Disorder Not Otherwise Specified
N/A - This is not my role
Rate your AGREEMENT with the following statement, considering both this article and any other
research and clinical literature you have read: "Night Eating Syndrome should be included as a
'disorder' in the upcoming, 5th edition of the Diagnostic and Statistical Manual (DSM-5)."
Neutral (no opinion)
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