Eating Disorders and Sleep: What Goes Wrong

Exploring the mechanisms by which eating disorders impair sleep.

Reviewed by Margaret Foley

Key points

• Impaired sleep is extremely common in eating disorders.
• At least 10 major factors contribute to this interference with sleep.
• Poor sleep affects health and quality of life and can make an eating disorder further entrenched.

This is the first post of a three-part series.

Sleep, eating, and sex are the big three evolved drives. I’ve written a couple of posts about sex, and this whole blog is about eating, but I’ve never dealt in a substantial way with sleep. If we ask how eating disorders and sleep interact, it’s a familiar story (one I told about cognitive impairment in a previous post): The disturbed eating disturbs sleep, which in turn disturbs the eating further. As with any feedback loop, it doesn’t really matter where the loop begins; what matters is how it gets and keeps itself entrenched—and what we can do about it.

Beyond the eating itself, there’s perhaps no feature of my life that was messed up as badly as sleep when I was ill, and that is as reliably excellent now that I’m better. It wasn’t so much the sleep quality or quantity that suffered during my anorexic years (though I’m sure quality wasn’t brilliant), but mostly the timing. For much of my anorexic life, I was up most of the night stringing out my presleep eating to heighten the feelings of control and therefore the fully “justified” pleasure of finally eating. It got so bad that sometimes I’d cycle through the entire 24 hours, staying up so late that I couldn’t even go to bed, and then “resetting” with weird afternoon sleeping, split sleeps with a bit of midnight eating in between, and maybe a few days of relatively ordinary bedtimes before things began to slip again. I remember some particularly awful times in the winter of my master’s when those two-phase nights were happening: Crashing out in the middle of the evening, forcing myself back up in the freezing cold at 1 or 2 a.m. to work and drink hot drinks, and then eventually eating before sleeping again through most of the morning. And now, well, I get sleepy around 10, usually drop off to sleep as soon as I close my eyes, and often wake a bit earlier than I’d like but feeling pretty well-rested after a solid eight hours. As in so many life domains post-recovery—stuff works again.

The correlations between sleep problems and eating disorders are widely documented, (e.g., Aspen et al., 2014; Cooper et al., 2020; Mehr & James, 2022; Mutti et al., 2023; Degasperi et al., 2024; Irish et al., 2024; Wilcox et al., 2024. Cooper et al. (2020) note, for example, that “Approximately 57% of those with EDs experience sleep problems, including difficulty falling asleep (the most common), parasomnia [abnormal behaviours during or around sleep], hypersomnia [excessive daytime sleepiness], early morning awakenings, and midsleep awakenings.”

Here’s a list of the most common factors that impair sleep when one has an eating disorder. As in many of my posts, I’ll focus on anorexia nervosa, but many of them apply in other EDs too.

• Hunger. This is clearly a major player. Someone with an eating disorder is typically attempting to eat too little, whether or not they are currently “succeeding.” It’s hard to fall and stay asleep when you’re hungry.
• Eating habits. Eating late at night (whether in the form of a binge or otherwise) can be a sleep disruption (though as we’ll explore in Part 2, it can also be a partial remedy). Deferring meals until right before sleep, for whatever reason (e.g., control, secrecy) can lead to extreme circadian disruptions, as I described above with reference to my own experience.
• Cold. If body fat and metabolic rate are diminished, persistent feelings of cold caused by low heart rate and poor circulation are often a problem, and unless you’re in a very hot climate, they can interfere with sleep.
• Pain. Joint and muscular pain are common in eating disorders, especially anorexia; so are muscle cramps caused by lack of minerals like potassium and magnesium. None of this helps with falling or staying asleep, and even the simple contact discomfort of lying on a flat surface when lacking body fat can make it hard to settle.
• Digestive problems. Gut issues are widespread, even the norm, in eating disorders. In anorexia, irritable bowel and constipation are caused by a combination of slowed transit times and loss of muscle strength, for example. This causes discomfort that interrupts sleep.
• Frequent urination or incontinence. Wastage of the pelvic floor muscles can lead to waking up frequently in the night. This can be exacerbated if you’re drinking excessive amounts of fluid—before bed or in general—to achieve a pseudo-satiety.
• Anxiety. Anxiety, both generalized and social, is a common consequence of disordered eating habits. Anxiety disorders are often diagnosed as comorbid with AN or other EDs, but a closer look at the data tends to reveal that they’re typically actually just a consequence of the eating and resolve when it does (Troscianko & Leon, 2020).
• Workaholism and exercise addiction. If you’re trying to work, exercise, or be otherwise “productive” all the time, it’s likely that you’ll lack good winding-down routines conducive to letting your body and mind relax toward sleep.
• Stress. Elevated cortisol and other disruptions to the hypothalamic-pituitary-adrenal (HPA) axis are common in anorexia and other eating disorders, suppressing melatonin production, diluting adenosine, and thus interfering with circadian rhythm.
• Meta-stress. In one of human psychology’s frustrating kinds of feedback, stress about the health effects of poor sleep can be a final contributor to poorer sleep.

All of this matters because sleep affects everything about how life feels. If you’re not sleeping well, many things will be working less well and feeling less good than they could (Zielinski, McKenna, & McCarley, 2016), including cognitive performance, emotion and mood regulation, appetite regulation, metabolism and energy, immune response, and cellular repair and renewal.

All the negative effects of poor sleep exacerbate the damage that the eating disorder is already doing. As Irish et al. (2024) remark, “Sleep problems may promote, exacerbate, or maintain ED symptoms through a variety of hypothesized mechanisms, such as impaired executive function, increased negative affect, and disruptions to appetitive rhythms.” By clouding your thinking, bad sleep can make the disorder seem less damaging. By making you feel more weak and hopeless, it can make recovery seem harder and less worth attempting. By affecting your appetite, and your knowing that it does, it can give you one more reason not to trust in what your body is signalling that it needs.

Of course, cause and effect can play out in different ways too. In the next part of this post, we’ll explore the workarounds that individuals invent to mitigate the effects of disordered eating on sleep, or of poor sleep on everything else—whether successfully or otherwise, in the short or longer term. In the third and final part, we’ll consider the need to endure things getting temporarily worse before they get better in recovery—and some ways of thinking about stepping out of the spiral.