Pennsylvania University. US: Experts have warned for years that insufficient sleep can lead to weight gain. A new Penn Medicine
study found that not only do we consume more food following a night of
total sleep deprivation, but we also we consume more fat and less
carbohydrates and a region of the brain known as the salience network
is what may lead us to eat more fat. The new findings are published in
Scientific Reports.
Most research in this arena has focused on changes in metabolic
hormones that lead to weight gain, while only a few have begun to
examine how changes in brain activity may play a role. “We wanted to
uncover whether changes in regional brain function had an impact on our
eating behavior following sleep deprivation,” says the study’s senior
author, Hengyi Rao, PhD,
a research assistant professor of Cognitive Neuroimaging in Neurology
and Psychiatry. “This work has implications for the approximately 15
million Americans who work the evening shift, night shift, rotating
shifts, or other employer arranged irregular schedules.”
The study took a unique approach and sequestered 34 sleep-deprived
subjects and 12 controls in a sleep lab for five days and four nights
for round-the-clock monitoring. All study subjects received one night of
regular sleep and were then randomized to either total sleep
deprivation or control for the remaining three nights. Baseline
functional MRI (fMRI) to examine brain connectivity changes associated
with macronutrient intake was conducted on all subjects the morning
following the first night of sleep. Sleep-deprived subjects were
matched to control subjects in age, body mass index (BMI), ethnicity or
gender.
On the second night, sleep deprivation subjects were kept awake
while the control subjects slept for eight hours. fMRI testing of both
groups continued on days, two, three and four at the same time each
day. All subjects had access to a variety of foods that they could
consume as desired.
Sleep deprived subjects consumed close to 1,000 calories during
overnight wakefulness. Despite this, they consumed a similar amount of
calories the day following sleep deprivation as they did the day
following baseline sleep. However, when comparing the macronutrient
intake between the two days, researchers found that healthy adults
consumed a greater percentage of calories from fat and a lower
percentage of calories from carbohydrates during the day following
total sleep deprivation.
The Penn researchers also found that sleep deprived subjects
displayed increased connectivity within the “salience network,” which is
thought to play a role in determining contextually dependent
behavioral responses to stimuli that can be either internal or
external, and is one of several key brain networks that carry out
various aspects of brain function. Moreover, increased connectivity in
the salience network correlated positively with the percentage of
calories consumed from fat and negatively correlated with the
percentage of carbohydrates after sleep deprivation. The salience
network is located toward the front of the brain and consists of three
sections, the dorsal anterior cingulate cortex, bilateral putamen, and
bilateral anterior insula. Activity in these structures is linked to
both emotion and bodily sensations, such as the heart racing, stomach
churning, pain, thirst, embarrassment, and attempting mental
challenges. Changes in caloric intake and content after sleep
deprivation may therefore relate to changes in the “salience” of food,
and in particular fatty food, in individuals who are sleep deprived.
“We believe this is the first study to examine the connection
between brain network connectivity and actual macronutrient intake
after baseline sleep and after total sleep deprivation,” says Rao. Most
similar studies rely on self-reported hunger levels of food cravings,
or on brain responses to pictures of different types of foods.
“Although this study examined the effects of acute total sleep
deprivation, similar changes may occur in response to the chronic
partial sleep restriction that is so prevalent in today’s society.”
Additional Penn authors on the study include Zhou Fang, Ning Ma,
Senhua Zhu, Siyuan Hu and John A. Detre or the Center for Functional
Neuroimaging; Andrea M. Spaeth, department of Sleep Medicine; and Namni
Goel and David F. Dinges, division of Sleep and Chronobiology.
The study was funded by the National Institutes of Health (R01
HL102119, R01 NR004281, R21 DA032022, R03 DA027098, P30 NS045839, CTRC
UL1RR024134), the department of the Navy, Office of Naval Research
(N00014-11-1-0361) and a pilot grant from the Institute of
Translational Medicine and Therapeutics at Penn.