Autistic circadian rhythms & sleep

But Pooh couldn’t sleep. The more he tried to sleep the more he couldn’t. He tried counting sheep, which is sometimes a good way of getting to sleep, and, as that was no good, he tried counting Heffalumps. And that was worse. Because every Heffalump that he counted was making straight for a pot of Pooh’s honey, and eating it all. For some minutes he lay there miserably, but when the five hundred and eighty-seventh Heffalump was licking its jaws, and saying to itself, “Very good honey this, I don’t know when I’ve tasted better,” Pooh could bear it no longer.

A.A. Milne, Winnie-the-Pooh

Dr. Natalie Engelbrecht ND RP says:

As a child, and even in my early adulthood, I slept well, and woke refreshed. At some point in the past 10 years, my sleep became awful. Gone was the less-than-5-minutes to fall asleep, replaced by tossing and turning. In addition, gone was the peaceful 8 hours of sleep; it was replaced by awakening throughout the night.

I attributed it to getting older. The longer and longer stretches of inadequate sleep affected my life terribly. It made me rely more and more on caffeine and become less capable of exercising. Which, of course, created a vicious cycle.

When I first got a biofeedback device, I was horrified by how badly my sleep had deteriorated. I began a journey of figuring out how to get good sleep again.

In the end, after months of trial and error, I figured out my circadian rhythm was off.

What is a circadian rhythm?

The term circadian rhythm originates from the Latin Circa, which means ‘approximately’, and dies, which means ‘day’. It refers to our body’s innate ability to follow a 24-hour clock. Our body does this based on temporal cues from our environment, such as light/darkness, mealtimes, exercise schedules, work schedules, etc.^[1]Coordination of circadian timing in mammals (Reppert & Weaver, 2002)^[2]Influence of chronotype and social zeitgebers on sleep/wake patterns (Korczak et al., 2008)

One internal mechanism which enables us to maintain this body clock is the period gene. In 1984, Drs. Hall and Rosbash discovered that this gene produces a protein in our cells over the course of 24 hours—during the night, protein levels accumulate in our cells; and then during the day, it degrades.

In 2017, this discovery led to both scientists winning the Nobel Prize in Physiology and Medicine.^[3]P-element transformation with period locus DNA restores rhythmicity to mutant, arrhythmic Drosophila melanogaster (Zehring et al., 1984) Since 1984, roughly a dozen new “clock” genes have been identified.

The hypothalamus region of our brain is responsible for regulating our circadian rhythms. This region receives sensory information, like light, from our environment, and uses it to adapt our bodily functions to the time of day. This includes regulation of our hormone levels, feeding behaviour, blood pressure, body temperature, metabolism, and of course, our sleep.^[4]Molecular mechanisms and physiological importance of circadian rhythms (Patke, Young, & Axelrod, 2020)

When there is a mismatch between our internal clock and the external environment, we can experience negative health effects until our bodies adjust to the change in rhythm. For example, we may experience jet lag from travelling. However, if this mismatch becomes long-term, it can lead to adverse health outcomes.^[5]Genomics of circadian rhythms in health and disease (Rijo-Ferreira & Takahashi, 2019)

Sleep/wake cycles

Light exposure & melatonin

Our sleep is most influenced by light exposure. When light from our environment enters our eyes, it gets translated into signals that are sent to our hypothalamus. These signals tell our brain how much of the hormone melatonin it should release.

The darker the environment, the more melatonin is released. Therefore, our melatonin levels are highest at night, preparing us for sleep by lowering our body temperature and blood pressure, and increasing our feelings of tiredness.^[6]Melatonin, an ubiquitous metabolic regulator: functions, mechanisms and effects on circadian disruption and degenerative diseases (Socaciu et al., 2020)

If you live north or south of the equator, daylight fluctuates seasonally. As such, melatonin rhythms also follow a seasonal clock. When there are fewer daylight hours during the fall and winter, we have more melatonin than in the spring and summer. This explains why many people feel more tired during the winter months.

Blue light & melatonin

Blue light inhibits melatonin release.^[7]Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans (West et al., 1985)^[8]Effects of blue light on the circadian system and eye physiology (Tosini, Ferguson, & Tsubota, 2016) Therefore, exposing ourselves to blue light keeps our body in “awake mode”. Today, blue light exposure is primarily a result of the LEDs used in TVs, computers, smartphones, and tablets. This suggests that we should avoid electronics before bed to restore our natural melatonin release and promote tiredness.

One popular way to limit blue-light exposure without completely cutting out electronics is the use of blue light-blocking glasses. However, thus far, results across clinical trials looking at the use of these glasses before bed show mixed results. They seem to improve insomnia symptoms in some neurotypical and neurodivergent (e.g. bipolar and depression) individuals but not all.^[9]Wearing blue light-blocking glasses in the evening advances circadian rhythms in the patients with delayed sleep phase disorder: An open-label trial (Esaki et al., 2016)^[10]Effect of blue-blocking glasses in major depressive disorder with sleep onset insomnia: A randomized, double-blind, placebo-controlled study (Esaki et al., 2017)^[11]Blocking nocturnal blue light for insomnia: A randomized controlled trial (Shechter et al., 2018)^[12]A double-blind, randomized, placebo-controlled trial of adjunctive blue-blocking glasses for the treatment of sleep and circadian rhythm in patients with bipolar disorder (Esaki et al., 2020)

Cortisol

Another significant influencer of our sleep/wake cycle is the hormone cortisol. Cortisol is best known as a “stress hormone,” but in reality, it regulates other things as well, like our M, immune functioning, and sleep. Cortisol levels are highest right after waking up, and decrease throughout the day.^[13]The human stress response (Endocrinol, Russell & Lightman, 2019)

This baseline daily rhythm of cortisol release explains why stress can have such a negative impact on our sleep. If cortisol also gets released in response to a stressor, these bursts of cortisol (in an acute event) or constant high levels of cortisol (in a chronic situation) inevitably disrupts our circadian rhythm, and thus also our sleep/wake cycle.

Sleep in Autism

It is reported that between 50-80% of autistic children experience sleep disturbances compared to ~30% of neurotypical children.^[14]A survey of sleep problems in autism, Asperger’s disorder and typically developing children, J Intellect Disabil Res, Polimeni, Richdale, & Francis, 2005^[15]Sleep Behaviors and Sleep Quality in Children with Autism Spectrum Disorders, Sleep, Souders et al., 2009^[16]Sleep in Children with Autism Spectrum Disorder, Curr Psychiatry Rep, Souders et al., 2017 While similar statistics are unavailable for autistic adults at this time, recent studies do suggest that autistic adults also experience more insomnia due to taking longer to fall asleep, experiencing more fragmented sleep, and waking up more often in the middle of the night.^[17]Sleep in adults with Autism Spectrum Disorder: a systematic review and meta-analysis of subjective and objective studies, Sleep Med, Morgan et al., 2020 Notably, studies also show that sleep disturbances in autistic adults correspond to a lower reported quality of life, including poorer mental and physical health.^[18]Sleep problems in autism spectrum disorders: Prevalence, nature, & possible biopsychosocial aetiologies, Sleep Med Rev, Richdale & Schreck, 2009^[19]Sleep determines quality of life in autistic adults: A longitudinal study. Autism Research, Deserno et al., 2019^[20]The impact of sleep quality on quality of life for autistic adults, Res Autism Spectr Disord, McLean, Eack, & Bishop, 2021

Circadian Rhythms in Autism

One prominent theory as to why autistics experience more sleep difficulty is that our internal clocks may not function with the same 24-hour rhythm. This is likely a result of different hormone regulation mechanisms, genetics, and processing of environmental stimuli.^[21]Are circadian rhythms new pathways to understand Autism Spectrum Disorder?, J Physiol Paris, Geoffray et al., 2016^[22]Biological Timing and Neurodevelopmental Disorders: A Role for Circadian Dysfunction in Autism Spectrum Disorders, Front Neurosci, Lorsung, Karthikeyan, & Cao, 2021

For example, data show that autistic children have lower levels of melatonin compared to neurotypical children.^[23]Evidence of pineal endocrine hypofunction in autistic children, Neuro Endocrinol Lett, Kulman et al., 2000 Moreover, there are data showing differences in genes that regulate circadian rhythms in autistics compared to the general population.^[24]The Possible Interplay of Synaptic and Clock Genes in Autism Spectrum Disorders, Cold Spring Harb Symp Quant Biol., Bourgeron, 2007 These findings suggest that our circadian rhythms may be disrupted, making it difficult to sleep.

Another theory is that autistics experience higher levels of arousal. We may have increased cognitive arousal because we tend to process information differently and we tend to have higher levels of anxiety than the general population. We may also have increased physiological arousal since we tend to be more sensitive to sensory stimuli.^[25]Sleep problems in children with autism spectrum disorder: examining the contributions of sensory over-responsivity and anxiety, Sleep Med, Mazurek & Petroski, 2015 This may result in increased variability of cortisol rhythms, making it more difficult to fall and stay asleep.^[26]Comparing cortisol, stress, and sensory sensitivity in children with autism, Autism Res, Corbett et al., 2009

Tips for improving your sleep as an autistic

Given the findings that so many autistics experience insomnia, and the well-documented relationship between poor sleep and poor quality of life, it is important for us to seek out strategies that help us get the sleep we need.

Here are some ideas for things you can try if you struggle with sleep:

• Ask your doctor about a melatonin supplement: In one study, melatonin given to autistic children 30 minutes before bed decreased the amount of time it took for individuals to fall asleep.^[27]Melatonin for sleep in children with autism: a controlled trial examining dose, tolerability, and outcomes, J Autism Dev Disord, Malow et al., 2012
• Reduce sensory stimuli before bed: Since we know that we tend to be more sensitive to sensory input, reducing as much input as possible may decrease our stress levels, arousal, and cortisol. This also includes engaging in cognitively stimulating activities. Sadly, diving into reading about your special interest right before bed is likely to keep you wide awake (and make you forget what time it is)!
• Reduce electronic use before bed: We know that screen use before bed in autistic children leads to poorer sleep.^[28]Bedtime Electronic Media Use and Sleep in Children with Autism Spectrum Disorder, J Dev Behav Pediatr, Mazurek et al., 2016 We also know that the blue light from electronic screens leads to a reduction in melatonin.
• You can also try out a pair of light-blocking glasses to decrease light exposure from electronics. Read The harms of blue light & a solution for more information.
• Avoid eating right before bed: While there isn’t any autistic-specific data to support this suggestion, we do know that our metabolism tends to slow while we sleep. However, if we have to digest a meal, our system is likely to stay awake.

You can read more about suggestions for improving your sleep, such as improving your sleep hygiene, in our previous article:

Autism & sleep problems: Solutions

What has Natalie found helpful?

Ultimately, our brains are all different, and we need to find a bedtime routine that works for our own body. For example, here is what Natalie has learned about her sleep:

Read the article below for more information on the problems with blue light, and how blue light-absorbing glasses could improve your sleep and address a myriad of other issues.

The harms of blue light & a solution