BOSTON—Patients with restless legs syndrome (RLS) are more likely to engage in nocturnal eating or have sleep-related eating disorder (SRED) than patients with psychophysiologic insomnia, according to research presented at the 26th Annual Meeting of the Associated Professional Sleep Societies. Dopaminergic agents reduced nocturnal eating and SRED by approximately half among patients with RLS.
Nocturnal eating, defined as breaking the overnight fast more than twice a month, can be dysfunctional or normal. “I would speculate that, in many cases, nocturnal eating is actually an intrinsic feature of RLS,” said Michael J. Howell, MD, Assistant Professor of Neurology at the University of Minnesota in Minneapolis. “It’s not merely an association, but it’s actually part of the condition.”
A Neurologic Basis for Nocturnal Eating?
Dr. Howell and colleagues followed consecutive adult patients with difficulty falling asleep because of RLS or psychophysiologic insomnia to determine whether nocturnal eating in RLS is a product of the patient’s awakenings or whether its roots are intrinsic to RLS. The researchers also sought to examine whether patients with RLS were more likely to manifest SRED when exposed to sedatives and to determine whether dopaminergic drugs affected nocturnal eating behavior.
Using a structured questionnaire and evaluation, the investigators identified more than 300 patients with difficulty initiating sleep. The majority of patients had conditions such as circadian rhythm delay or chronic pain and were excluded. A total of 130 patients had RLS or psychophysiologic insomnia. A total of 88 patients had RLS, and 42 had psychophysiologic insomnia.
Nocturnal Eating More Common in RLS
Of patients with RLS, 61% engaged in nocturnal eating, and most of them did it at least three times per week. In contrast, only 12% of patients with psychophysiologic insomnia engaged in this behavior. Results were also striking for SRED in RLS. Approximately 36% of RLS patients described the dysfunctional binge eating of SRED, but no psychophysiologic insomnia patients described dysfunctional nocturnal feeding behavior. About 80% of patients with RLS who had previously been exposed to a benzodiazepine receptor agonist described a history of sleepwalking or SRED, compared with 12% among patients with psychophysiologic insomnia. Compared with patients with RLS, patients with psychophysiologic insomnia were more likely to be awake at night for a prolonged period of time, but less likely to eat.
Before beginning dopaminergic treatment, 68% of patients with RLS had nocturnal eating, and dopaminergic agents reduced this rate by half. Dopaminergic agents also halved the incidence of SRED among patients with RLS, but the number of cases was insufficient to achieve statistical significance.
The investigators observed no cases of de novo nocturnal eating or SRED once patients with RLS started taking dopaminergic agents. The coincident decrease in RLS and nocturnal eating “suggests that nocturnal eating in RLS is fundamentally different from the other impulse discontrol issues, such as gambling, that occur in RLS treatment,” said Dr. Howell. Evidence from previous studies supports this hypothesis, he added.
“This investigation helps confirm that amnestic SRED is rare in the absence of sedative–hypnotic medications,” Dr. Howell commented. “Amnestic SRED was common in the setting of sedative–hypnotic use among RLS, but not in psychophysiologic insomnia patients. Our study is also consistent with previous reports that SRED and sleepwalking are rare in patients who have been given zolpidem when RLS has been rigorously excluded,” he concluded.
Howell MJ, Schenck CH. Restless Nocturnal Eating: A common feature of Willis-Ekbom Syndrome (RLS). J Clin Sleep Med. 2012;8(4):413-419.
Provini F, Antelmi E, Vignatelli L, et al. Association of restless legs syndrome with nocturnal eating: a case-control study. Mov Disord. 2009;24(6):871-877.