Lack of Sleep Makes Us Eat More
Multiple studies now support the fact that a lack of sleep changes brain activity and increases the urge to eat more. Sleep deficiency also produces the inclination to eat more high calorie foods.
Brain function studied
Research was conducted using functional magnetic resonance imaging (fMRI) in order to analyze the relationship between brain function and eating habits among 23 human test subjects.
The subjects were tested after having a good night’s sleep, and then tested after having a bad night’s sleep. The good night’s sleep consisted of enough sleep to feel fully rested and awake during the day, and the poor night’s sleep resulted in daytime sleepiness.
After the poor night’s sleep the subjects were found to have less activity in the frontal cortex of the brain, while having increased activity in the amygdala part of the brain.
Increased activity in the frontal cortex has been linked in other research with healthier eating habits, while more activity in the amygdala has been linked with eating more, weight gain and binge eating – especially high-calorie foods.
The researchers also found that those who had the most sleep deprivation had the greatest amygdala activity – indicating the urge to eat high-calorie foods becomes greater as our sleep becomes worse.
The researchers concluded that,
“These findings provide an explanatory brain mechanism by which insufficient sleep may lead to the development/maintenance of obesity through diminished activity in higher-order cortical evaluation regions, combined with excess subcortical limbic responsivity, resulting in the selection of foods most capable of triggering weight-gain.”
The findings of this study confirm a study last year by researchers from the Department of Neuroscience at Sweden’s Uppsala University. Here the researchers tested 12 healthy men who were studied with brain scans along with food cravings and appetite, and blood sugar testing, after a poor night’s sleep (sleep deprivation) and after a good night’s sleep.
In this study the researchers – using functional magnetic resonance imaging – found that sleep deprivation caused brain activity to increase in the right anterior cingulate cortex as the subjects watched images of foods.
The emotional part of the anterior cingulate cortex links to the amygdala – providing the association between the results of these two studies.
To provide confirmation of the link between increased activity in the anterior cingulate cortex, the researchers found that appetite scores among those with increased anterior cingulate cortex activity were higher than among those with less brain activity in that region.
Blood sugar affected
These brain-activity changes among the sleep-deprived subjects also resulted despite no difference in the subjects’ relative blood glucose levels, between the poor night’s sleep and the good night’s sleep testing. This indicates that the relationship between sleep and eating is not related to a change in blood sugar levels during sleep – but specifically on brain activity.
The researchers concluded:
“These results provide evidence that acute sleep loss enhances hedonic stimulus processing in the brain underlying the drive to consume food, independent of plasma glucose levels. These findings highlight a potentially important mechanism contributing to the growing levels of obesity in Western society.”
These studies confirm other research tying obesity and overeating to sleep deprivation.
Lack of Sleep Causes Overeating
Research from Columbia University’s College of Physicians and Surgeons has determined that sleep deficit creates a greater propensity to eat and produces increased brain activity related to food stimulus.
The researchers conducted their study, supported by a grant from the National Institutes of Health, on twenty-six healthy men and women of normal weight. They set up two groups, which crossed over between having six days of too little sleep and having six days of getting plenty of sleep. Four hours a night was considered too little sleep, while nine hours a night was considered plenty.
At the end of each six-day period, the researchers performed neuron activity scans using magnetic resonance imaging (MRI). The subjects were given sensory contact with food while they were in the MRI scanners, allowing researchers to track and compare their brain responses. The subjects were tested while in a fasting state to amplify the results.
The MRI scans determined that the subjects’ brain activity in regions associated with reward and pleasure was greater among those subjects who had too little sleep during the past six days.
The brain regions associated with reward – known to be activated during eating and other pleasurable activities – are the prefrontal cortex, the thalamus, the nucleus accumbens, and the insula regions. These areas all lit up with greater activity for the sleep deprived in response to food.
This study confirms other research that has shown that sleep is associated with overeating and obesity. In 2011, researchers from the New York Obesity Research Center and St Luke’s-Roosevelt Hospital found that sleep deficit increased calorie intake. This study tested 15 men and 15 women who either slept for four hours or nine hours for five days straight. During the period they measured the subjects calorie intake and calorie metabolism.
They found that the sleep-deprived expended the same amount of average energy, but consumed a greater number of calories and more fats – especially saturated fats. The sleep-deprived subjects consumed about 300 more calories per day, almost 21 more grams of fat and nearly 9 more grams of saturated fat per day than the normal sleep subjects consumed.
Other studies of larger populations have found those who sleep less had greater obesity incidence. In a recent study from The Australian National University of 60,569 human subjects, women who slept less than six hours were 49% more likely to be obese and men who slept less than six hours were 36% more likely to be obese.
So it looks like a start to any successful weight loss diet is a good night’s sleep.
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