Sleep-Eating Binges: A Silent Cause of Obesity

A chemical compound reaction?

Posted May 29, 2019

A nightmare may go like this: You take a popular fast-acting prescription sleeping pill and fall asleep quickly, but awaken several hours later with a compulsion to eat. You eat quickly and indiscriminately. And because you are not really awake, sometimes you may even put non-edible things like a coffee stirrer in your mouth and chew that. Eventually, you stop eating, wake up enough to go to bed, and go back to sleep. The next morning you have no appetite, but also no memory of what happened in the night.  If you continue taking the sleeping pill, you find that you are gaining weight.

Another version: Your psychiatrist prescribes a very effective antidepressant and encourages you to take it because it might finally relieve your depression. You do so, but after a few days, you are in the kitchen in the middle of the night eating voraciously—but you are asleep. If someone tries to wake you up and stop you, you become agitated and continue to eat. The next morning you have no recollection of eating, but as this continues night after night, you find yourself rapidly gaining weight.   

Your nighttime eating seems to resemble something called binge eating disorder, a type of eating disorder almost always associated with weight gain and eventual obesity. The symptoms include eating:

  • Much more rapidly than you normally do
  • Until you are so full you feel uncomfortable
  • Large quantities of food when you are not physically hungry, and
  • Alone because you are embarrassed at anyone seeing how much you eat and feeling very upset and distressed at what you are doing.

Of course, you have no memory of eating this way at night, but others in the household tell you that is what you are doing. Do you have a binge eating disorder? You may be suffering from SRED, a sleep-related eating disorder. It is characterized by the rapid consumption of excessive amounts of food over a short period of time when not hungry, and usually is not associated with taking a sleeping pill or an antidepressant. Superficially, it looks like daytime binge eating disorder. However, unlike binges during the day—which may be planned carefully to occur when no one is around and the food carefully chosen and stocked in the house—the nighttime binges are unplanned; what is eaten may be random and the eater is asleep. The eater has partial or total amnesia; there is no recollection of the eating binge the next morning. The nighttime binges usually occur within one to three hours after falling asleep, but some people may wake up as many as five times a night to binge.

A majority of patients with SRED have experienced other sleep disturbances such as restless leg syndrome, periodic limb movements of sleep (PLMS), or somnambulism (sleepwalking). Dopamine, a brain neurotransmitter, may be involved in causing this sleep disturbance, because it is implicated in restless leg syndrome.

The incidence of SRED in the general population is extremely low, according to the paper by Inoue, but higher among people with daytime binge eating disorder. However, recent reports have linked the use of Zolpidem (Ambien) and the antidepressant Mirtazapine (Remeron) with sleep-related eating disorder. The reports of amnesia-associated eating binges following the use of Zolpidem are still rare, but enough reports have been published to recognize this as a side effect. People who have been affected stop their nighttime binging once they stop taking the medication.

The same is true among patients who are treated with Mirtazapine. Although the drug works on enhancing serotonin release, it is thought that the voracious nighttime eating may be due to activation of another neurotransmitter, histamine. Stopping the medications that cause SRED is the most effective way of treating this eating disorder. Treatment with an anti-epileptic medication, Topiramate, has been somewhat effective according to the article by Jeong, although side effects from this drug have somewhat diminished its utility.

The question of what in the brain is triggering these nocturnal eating episodes is still unknown, especially for those whose SRED is not a side effect of their medications. There has been much written about daytime binge eating disorder, and although the disease is not well understood, the binges are often associated with acute or chronic emotional distress. However, daytime binges are not limited to negative moods, but may take place during or following positive emotional states. Both daytime and nighttime binge eating share the compulsion to consume large volumes of food quickly, but since the nighttime binger is unaware of what he or she is doing, the eating is not provoked by conscious emotional states (as it may be during the daytime binges).  

SRED may offer an opportunity to study how the brain’s control over hunger and satiety is unable to halt these bouts of abnormal food intake. Clearly, the nighttime binger is unable to stop consciously through will power, to recognize that enormous amounts of food are being eaten, or even to perceive the physical sensation of fullness since he or she is asleep. Might the daytime binge eater be equally susceptible to the same inability of the brain to control food intake? Currently, one of the diagnostic features of binge eating disorders is that the binge eater cannot control food intake. But what if it is the brain, and not the willpower of the binger, that has no ability to control food intake?

The daytime binger finds himself or herself eating out of control and of course looks for a reason: “I must be feeling sad, stressed, angry, tired, happy, euphoric, anxious and/or guilty.” The nighttime eater has no idea what is happening, no perceived change in emotional state, no memory of it, and no guilt. If our brains were computers, we would say it is a software problem and not a problem caused by the user. Perhaps SRED will allow us to see the brain glitch behind the binges. 

References

“Sleep‐related eating disorder and its associated conditions,” Inoue Y, Psychiatry and Clinical Neuroscience 2015; 69: 309-320; “Sleep-Related Eating Disorders,” Auger, R, Psychiatry 2006; 3: 64–70.

“Zolpidem and Amnestic Sleep Related Eating Disorder,” Najjar M, J Clin Sleep Med. 2007 3: 637–638; “Sleep-Related Eating Disorder Associated With Mirtazapine,” Jeong J-H, J Clin Psychopharmacol. 2014 34: 752–753