Circadian Rhythm, Sleep May Influence Risk of Anorexia Nervosa, Study Finds

Anorexia nervosa was associated with insomnia and had a bidirectional relationship to morning chronotype, but was not linked to other sleep traits, according to a study recently published in JAMA Network Open.

Chronotype refers to an individual’s preference towards the morning or the evening. As the authors of the present study note, a person’s circadian rhythm influences someone’s chronotype due to its impact on sleeping patterns, among other regular bodily processes. To date, patterns in circadian rhythms have been loosely implicated in certain eating disorders such as binge eating, which has been linked to evening chronotype.

Model of Anorexia Nervosa/Anxiety About Weight | image credit: terovesalainen - stock.adobe.com

In this realm, anorexia nervosa has become a disorder of increasing interest. Those affected by this disorder are known to drastically restrict food consumption, experience weight loss, and have serious anxieties regarding gaining weight. Past evidence has suggested a correlation between circadian rhythm and anorexia nervosa in instances of lacking appetite in the mornings, for example. Additional studies have demonstrated the phenomena of early morning awakening insomnia in those with anorexia nervosa—suggesting a disturbance in sleep-wake cycles. However, overall research exploring associations between anorexia nervosa and circadian rhythm and sleep is lacking. To address this gap in knowledge, researchers conducted a study to explore these relationships with Mendelian randomization (MR, which measures gene variation to evaluate causal effects) and polygenic risk scores (PRS, where higher scoring indicates a higher risk for a disease).

Between February and August 2023, data were gathered on patients of European ancestry using a genome-wide association studies (GWAS) meta-analysis. Additionally, electronic records were largely assessed from the Mass General Brigham (MGB) Biobank. With the MGB Biobank, a PRS for anorexia nervosa was created for every patient, and their associations with prevalent sleep disorders (taken from electronic health records) were tested.

The GWAS for anorexia nervosa consisted of 16,992 cases alongside 55,525 controls. Results showed a bidirectional relationship between morning chronotype and anorexia nervosa: the genetic liability for morning chronotype was linked with higher risks for anorexia nervosa (β = 0.178; 95% CI, 0.042-0.315), and genetic liability for anorexia nervosa also contributed to higher likelihood for a morning chronotype (β = 0.039; 95%CI, 0.006-0.072). A secondary analysis of this association was conducted and revealed consistent results when analyzing for binary chronotype (morning vs evening preference) as the primary outcome (β = 0.014; 95%CI, 0.002-0.026).

The MR analysis found a correlation between insomnia and heightened risk for anorexia nervosa. This was not a bidirectional association; however, genetical liability for insomnia was linked to higher risk of anorexia nervosa (β = 0.339; 95%CI, 0.052-0.627). These results were confirmed with an additional sensitivity analysis (P < .001). Researchers did not observe any connection between sleep duration, daytime napping, daytime sleepiness, and anorexia nervosa.

In their analysis utilizing the MGB Biobank, a total of 47,082 adult patients were assessed. Upon the creation of PRS for each patient, researchers witnessed that for each standard deviation increase in PRS, an individual had a 36% higher chance of anorexia nervosa (odds ratio [OR], 1.36; 95%CI, 1.14-1.6). No significant associations were seen in regard to sleep apnea, time in bed, social jetlag, sleep debt or midpoint, or restless leg syndrome.

Researchers’ findings indicate that anorexia nervosa may have a circadian feature. Although they state that the clinical implications of their results are currently unclear, they conclude by highlighting the potential avenues for future research in this area. Further consideration of morningness as a potential risk factor for anorexia nervosa could present clinical benefits in the treatment and prevention of this disorder. Furthermore, the researchers foresee their study directing research efforts toward circadian-based mechanisms as a potential treatment approach for individuals affected by anorexia nervosa.

Reference

Wilcox H, Paz V, Saxena R, Winkelman JW, Garfield V, Dashti HS. The role of circadian rhythms and sleep in anorexia nervosa. JAMA Netw Open. 2024 Jan 2;7(1):e2350358. doi: 10.1001/jamanetworkopen.2023.50358