Sleep Problems and Eating Disorders: Something to Sleep On
Sleep problems are often characterized as trouble falling asleep, staying asleep, difficulty waking from sleep, feeling sleepy or tired during the daytime, or experiencing abnormal sleep behavior (e.g., sleep-walking). Sleep problems can also lead to sleep deprivation or insufficient sleep. Sometimes these problems cluster together, such as difficulty falling asleep, staying asleep, and waking from sleep, which are the symptoms of sleep disorder insomnia.(1) Sleep problems like those experienced with insomnia or other sleep disorders (e.g., hypersomnolence or sleeping too much, circadian rhythm sleep-wake disorder) are diagnosed when the problems persists for at least one month.(1) Usually researchers evaluate sleep problems over the past month;(2) however experimental studies often look at the effects of more short-term sleep deprivation (e.g., less than a week) on both physical and psychological health.(3)
What do we know about sleep and eating disorders?
Sleep problems have been studied in eating disorders, including anorexia nervosa (AN), bulimia nervosa (BN), binge-eating disorder (BED), and night eating syndrome (NES; see below for comprehensive reviews).(4, 5, 6) For example, Kim et al.(7) found approximately half of female patients with AN or BN were currently experiencing sleep problems, including about 33% having trouble falling asleep and about 18% waking up throughout the night. As for BED, Vardar et al.(8) reported that patients with BED and obesity had more sleep problems, such as poor sleep quality and shorter sleep duration, compared to patients who were obese but did not have BED and compared to normal weight individuals. NES, which involves nighttime consumption of at least 25% of daily food intake after the evening meal, has an established overlap with sleep problems such as insomnia.(4) More broadly, sleep problems have been associated with binge eating in studies of female twins,(9, 10) and sleep problems have also been associated with binge eating and purging behaviors in studies of college men and women.(11-16)
What explains this connection?
Clearly, research supports a connection between sleep problems and eating disorders, but we don’t have an explanation for the connection, although several theories have been proposed.(4, 5, 6) Allison et al.(4) review this research and highlight weight fluctuations (gain and loss) and disruption of appetite-regulating hormones as one possibility. In fact, studies have suggested that sleep deprivation contributes to weight gain and obesity(17) and can cause disruption of appetite-regulating hormones, resulting in increased hunger.(17, 18) This is supported by the fact that individuals with eating disorders are known to have disruptions in appetite-regulating hormones as well as weight fluctuations.(19)
Depressed mood may also explain the connection between sleep problems and eating disorders. Sleep problems, particularly sleep deprivation, increase risk for depression,(1) and frequent insomnia or daytime fatigue are actually criteria for the diagnosis of depression.(20) Supporting this is the high overlap between eating disorders and depression; with lifetime co-morbidity (overlap) with AN, BN, and BED of 39%, 50%, and 32%, respectively.(21) These factors and possibly others (e.g., personality traits, genetic predisposition, reward sensitivity) may contribute to the connection between sleep problems and eating disorders.
Why is this important?
Understanding the connection between sleep problems and eating disorders may inform future prevention and intervention programs and treatments. Indeed, bright light therapy,† which is also used to effectively treat seasonal affective disorder(22) and various sleep disorders, has shown promising results in treating BN(23, 24, 25) and NES(26) in pilot studies. It remains unclear which comes first—sleep problems or the eating disorder. Most likely, both paths are possible. Allison et al.(4) review assessment tools, including self-report questionnaires and actigraph watches, that can be used both clinically and in research. All of this is particularly noteworthy as sleep deprivation has continuously increased in the general population over the last few decades.(18) Further and more detailed studies of the nature of the relationship between sleep and eating disturbances are relevant not only for individuals with eating disorders, but also for the general population.