Chips, dips, cookies, chocolates, eggnog: These are among the temptations
posed by the highly palatable, high-calorie snacks commonly served at winter
evening social events that intensify the struggle people with night eating
syndrome (NES) face year round.
People with NES overeat in the evening and even awaken from sleep to eat
one to two times a night on average, according to Kelly Allison, Ph.D. They
consume one-quarter or more of their daily food intake after their evening
meal, said Allison, a research assistant professor of psychology in psychiatry
at the University of Pennsylvania School of Medicine and director of a
NES-focused cognitive-behavioral therapy (CBT) study.
People with NES typically lack appetite in the morning. Some curb their
daytime food intake, knowing they will graze after dark.
NES was first described in 1955 by Albert Stunkard, M.D., a professor of
psychiatry, director emeritus of the University of Pennsylvania's weight and
eating disorders program, and still an active investigator in the field.
While holiday-related stress boosts NES in some people, whether reduced
winter daylight exposure also contributes to the disorder is still being
explored. Allison, Stunkard, and colleagues are tracking people with NES and
control subjects in Philadelphia and Stockholm, Sweden, in winter and summer
to see if eating behavior varies by season.
Occurring in about 1.5 percent of the general population, NES is more
common than anorexia nervosa, which affects less than 1 percent of the
population, mainly young women, Stunkard said. People with NES rarely binge
About 7.6 percent of obesity clinic patients report symptoms of NES, as do
12 percent of those visiting outpatient psychiatric clinics for any disorder.
Among people awaiting bariatric surgery, 10 percent to 27 percent have NES,
two studies have suggested. DSM-IV-TR classifies NES as an eating
disorder not otherwise specified.
Not all people with NES are obese. Some maintain normal weight via daytime
food restriction or intensive exercise. These individuals typically are
younger by about a decade than obese people with NES, suggesting NES may serve
as a pathway to obesity, Stunkard noted.
Many people with NES keep a small refrigerator next to the bed, favoring
peanut butter, popsicles, candy bars, nuts, and sometimes fruit as handy
middle-of-the-night snacks. They rely on food as an aid to returning to sleep,
probably a conditioned response, Allison reported.
People with NES remember what they eat in the night, unlike people with
sleep-related eating disorder (SRED), a rare parasomnia. Those with SRED often
have only partial recall of having consumed frequently unpalatable items, such
as buttered cigarettes, raw bacon, or cat food.
Allison, Stunkard, and colleagues assessed 25-hour profiles of circulating
glucose and seven hormones in relation to food intake, sleep, and stress in 15
women with NES and 14 matched controls, reporting results in the November 2005
Journal of Clinical Endocrinology and Metabolism.
Participants spent three nights in a general clinical research center at
Penn. They received three meals a day and had ad libitum access to snacks,
including foods brought from home, placed on a bedside table at night.
Both groups had a similar total daily caloric intake, averaging about 2,900
kcal. NES subjects ate far more at night, consuming four times more fat and
twice the amount of carbohydrates and protein between 8 p.m. and 8 a.m. than
control subjects. All NES subjects awakened to eat at least two of their three
nights in the hospital, compared with only one control subject.
"We found no evidence of an endocrine etiology for night eating in
this very careful study," Stunkard said. This work, he added, corrects
findings from an earlier, smaller study suggesting NES might involve a
disturbance of appetite-regulating hormones.
"We think NES represents a dysregulation of circadian patterns of
food intake, but without disruption of the circadian sleep pattern," he
explained. "NES is primarily an eating disorder, and only secondarily a
sleep disorder." While appetite normally shuts down in sleep, NES
appears to be a rare clinical example of an uncoupling of eating and the
sleep/wake cycle. Its cause has not been determined.
John O'Reardon, M.D., an assistant professor of psychiatry at Penn, working
with Allison, Stunkard, and others, randomly assigned 17 outpatients with NES
to receive sertraline and another 17 to receive placebo in an eight-week,
double-blind, flexible-dose (50 mg to 200 mg a day) study. They found 12
subjects in the sertraline group, but only three in the placebo group, much
improved or very much improved, according to the Clinical Global Impression of
Severity Scale. Overweight and obese subjects in the sertraline group lost
more weight by week 8 than those on placebo. The researchers' report is in
press with the American Journal of Psychiatry.
In a novel long distance study, perhaps the first of its kind, according to
Stunkard, the Penn team recruited 50 patients who described symptoms
consistent with NES on a website questionnaire, and whose physicians agreed to
provide treatment with sertraline for eight weeks at dosages suggested by the
Penn investigators. Patients completed survey forms every two weeks. Success
rates were comparable to those in the single-and double-blind trials. A report
is in preparation.
Allsion, meanwhile, enrolled 16 adults with NES in a 10-session, 12-week
trial of NES-focused CBT, the first study of CBT for the disorder.
Since many people with NES eat chaotically in the daytime, Allison
encouraged them to keep food diaries, eat more systematically, and choose
snacks smaller and lower in calories. She also advised them to get food out of
the bedroom. "Once they do that," she said, "they have less
reason to wake up, so they awaken less often."
Nine subjects completed the study, cutting their middle-of-the-night
snacking from six to 0.3 times per week. Completers also lost a significant
amount of weight by the study's end, she reported at Obesity Society meetings
in Vancouver, British Columbia, in October 2005.
"While people with NES who stay on sertraline continue to do
well," Allison notes, "learning CBT strategies may give them a
better long term prognosis."
Resources for patients about night eating syndrome include
Overcoming Night Eating Syndrome: A Step-By-Step Guide to Breaking the Cycle
by Kelly Allison, Ph.D., Albert Strunkard, M.D., and Sara Their (New
Harbinger Publications, 2004) and the University of Pennsylvania Web site at<www.med.upenn.edu/weight/nighteating.shtml>.▪