Insomnia in Autism and Anorexia

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What do autism and eating disorders have to do with sleep? Much like digestion, sleep can be affected by both in different ways – so if you’re on the spectrum, struggling with an eating disorder, and having trouble sleeping, there is an explanation! Actually, multiple explanations; the science is complicated, and the research on what exactly causes what is not conclusive, but there’s enough out there to clarify why you’re lying awake for hours at night, staring at the ceiling, wondering why your body’s not doing what it’s supposed to do.

Circadian Rhythm

Let’s start with the basics: if you can think back to high school biology class, you probably know what a circadian rhythm is. Basically, it’s a 24-hour clock in your brain that regulates cycles of alertness and sleepiness, based on environmental cues like the rising and setting of the sun. Your circadian rhythm is actually involved in a lot more than just sleep; it evolved to help humans adapt to all kinds of changes in their surroundings, like temperature, radiation, and food availability. A lot of your bodies’ internal processes, like digestion and the release of hormones, rely on this system functioning well.

Sleep alone is a multifaceted process, responsible for a lot more than just physical restoration. It’s a time for your body to repair, and for your brain to consolidate memories and process emotional information. There’s a reason why you’re stressed and forgetful when you’re sleep deprived - your brain missed out on a crucial period of physical and mental recovery! I also believe that’s why autistic people tend to need more sleep than neurotypicals, as our brains are constantly at work, trying to manage the overstimulation of a world that wasn’t built for us!

Here’s a little more science: the suprachiasmatic nucleus (SCN) is the “pacemaker” of your circadian rhythm; it’s located in the anterior (front) of your hypothalamus, and receives your body’s signals about changes in light. During the day, the SCN delivers a signal that sets off a complicated chain of events (too long to get into here!) that essentially inhibits your sympathetic nervous system and prevents melatonin from being released.

Autism and Melatonin

You’ve probably heard of melatonin before – those pill bottles lining the shelves at CVS, promising you quicker and more satisfying sleep. But melatonin isn’t just the name of a medication - it’s a hormone produced by your pineal gland (a.k.a. your “third eye,” because its primary function is to let in light and darkness.) At night, the departure of light signals retinal cells (in your eyes) to inhibit the SCN, which, through another long chain of events, stimulates the parasympathetic nervous system to induce sleepiness and secrete melatonin. 

So, back to the original question: what does all this have to do with autism and eating disorders? To start, studies have shown lower melatonin concentrations in autistic individuals. The mechanics of this vary in the research; some studies show abnormal circadian rhythms, while others show gene abnormalities that could contribute to reduced melatonin production. These studies also show improvement from melatonin supplementation, so it actually might be worth checking out those CVS bottles after all! I personally take a very small dose of melatonin each night – we’re talking 0.5mg – which is a dosage I would suggest if you’re struggling with sleep or even have had negative experiences with taking melatonin in the past. I order these gummies on amazon, as they're easy to cut in half!

Insomnia in Eating Disorders

When it comes to insomnia and eating disorders, the research is more complex. There is a lot of correlational evidence – for example, undereating being linked to sleep problems – but the causal relationships aren’t 100% clear. This is because, as I’m sure you know, eating disorders often come with a lot of other psychological problems – anxiety, depression, OCD, and more. All of these “comorbid disorders” can individually create disturbances in sleep, so when studying the effects of eating disorders on sleep duration and quality, there are a lot of intersecting factors to consider. 

Regardless, there is a wealth of research to support the claim that eating disorders aren’t great for sleep. Some studies have found that anxiety and depression significantly mediate the relationship between insomnia and ED psychopathology, which basically means that eating disorders influence sleep through the psychological distress they create. In order for a study to narrow down whether eating disorders directly influence sleep, it would have to control for comorbidities like depression. And this doesn’t take comorbid autism into account, an overlap that is just so under-recognized in the world of eating disorders. But hey, that’s what I’m here for :)

There was one study that adjusted for baseline depressive symptoms and they found that the association between eating disorders and sleep disturbances remained statistically significant, but the relationship was weaker. This means that even without comorbidities like anxiety and depression, eating disorders still impair sleep quality, but the overall impact is stronger when coupled with other disorders. So again, someone with an eating disorder that is also autistic will most likely have an exponentially harder time falling asleep that someone who either “just” has an eating disorder or someone who “just” is autistic.

Can Food Restriction Cause Insomnia? 

Is nutritional deficiency on its own enough to mess with your sleep? There is a lot of research to suggest that the answer is yes. One study on the relationships between sleep, nutrition, and mood found that sleep disturbances in patients with anorexia were more closely associated with changes in nutritional status than with changes in emotional state. This was especially pronounced in patients who developed anorexia during puberty. The release of human growth hormone during sleep is directly related to “slow-wave sleep” (SWS), which is reduced in patients with anorexia. I actually found this last statistic SUPER interesting, because when I was at a healthy weight in recovery but still wasn’t growing taller, I got my growth hormones tested to see if I was eligible to receive hormonal treatment. My growth hormones were within normal range, but they were at the super low end. I guess there’s never any way of knowing exactly how much an eating disorder impacted my growth considering it started when I was just 11, but as I write in my book Rainbow Girl: "I will remain shorter than my potential height had I never gotten an eating disorder. But I did get an eating disorder, and the journey to recovery has taught me life lessons that could never measure up to a marking on the wall."

The Stages of Sleep

A quick explanation on SWS and the stages of sleep: until the 1950s, people thought sleep was a fairly simplistic, passive process. Then, scientists started measuring brain activity during sleep using an electroencephalogram, or an EEG. They discovered that sleep is actually an incredibly complex and active process, with multiple stages. When you’re awake, your brain produces high-frequency “beta waves.” As you progress through the stages of sleep, the frequency of those waves decrease. So by stage 4, your brain is producing “delta waves,” a.k.a. slow wave sleep, or deep sleep. Multiple studies have found that patients with anorexia have lower amounts of SWS.

Eating Disorders and Slow Wave Sleep

Why is this? There are many possible explanations. One is that eating disorders slow your metabolism during both sleep and wakefulness, which alters SWS. Another is that anorexia has been linked with certain peptide abnormalities. (Peptide hormones are hormones made up of small chains of amino acids, which are building blocks for proteins. They’re involved in regulating your metabolism and energy levels.)

Ghrelin and leptin - our hunger and fullness hormones - are two peptides involved in the relationship between eating and sleep. In anorexia, ghrelin is elevated and leptin is reduced. The causal relationship between these peptides and sleep is still not fully understood. However, in animal studies where researchers induced hunger (i.e. increased ghrelin), their subjects had reduced SWS and increased nocturnal wakefulness. Some studies suggest that malnutrition is the root cause of this phenomenon, while others point more towards the psychological symptoms. Either way, sleep, nutrition, and emotional wellness are intimately connected, so if you’re struggling with one, it’s not at all surprising if the others start to slip as well. You are not alone, and there are plenty of reasons to be hopeful. Your body is resilient; when you tend to one piece of this puzzle, it’s likely the other pieces will fall into place as well!

Does Weight Restoration Improve Sleep?

Here’s a real-world example: in a 2016 study on 50 female patients with anorexia, weight restoration had a powerful impact on sleep quality. Before restoration, their total sleep time and onset sleep latency (i.e. the time it took them to fall asleep) was significantly higher than healthy patients. After weight restoration, however, both factors improved so much that there was very little difference between the two populations!

There is no magic pill, especially if you’re struggling with multiple things at once - eating, sleeping, and being autistic in a world designed for neurotypical people. Similar to healing digestion, it will likely take multiple approaches before you start to notice a difference. Your body is incredibly smart, but it’s not a machine either – if it’s under multiple forms of stress (mental or physical), then its balance will obviously be thrown off!. If you go to bed hungry, it will try to get you to eat by keeping you awake. If you are constantly overwhelmed and overstimulated, it will “shift gears” into a state of hyper-alertness, which hundreds of years ago might have helped you outrun a predator, but now in the twenty-first century isn’t so useful. Whatever you can do to ease your body out of that hypervigilance – whether it be coaching with me, therapy, medication, meditation, or something else – could make a huge difference. It will take time, but little things add up. I always say: small consistent steps over time lead to the biggest changes. Before you know it, there will be no more counting sheep and staring at the ceiling. Your body will just drift off because it knows it’s safe.

 Sources:

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