Rhythm & Blues: How a Broken Clock Breaks the Mind
In the past, people believed that our bodies and minds are distinct entities, a view called mind‑body dualism, where mental phenomena are considered non‑physical.
The idea fueled the stigma that still clings to mental health. Yet our minds, our consciousnesses, are built on the physical, biological substratum of the brain. In reality, body and mind are inextricably intertwined: a well mind depends on a healthy brain.
Readers of my blogs are already familiar with a critical part of our brains, a collection of cell bodies in the hypothalamus called the suprachiasmatic nucleus. The principal purpose of this organized group of cells is to keep our physiological rhythms synchronized with the outside world. Light and the absence of light trigger the SCN to dispatch timing signals throughout the body, and thereby align countless biological processes to the time of day. When that synchrony unravels, our minds are at higher risk of unravelling too.
But like most human physiology, it's not that simple. Research shows a bidirectional relationship: mental health disorders frequently disturb daily rhythms, and rhythm disruption can, in turn, trigger or worsen psychiatric symptoms.¹ Let’s explore the mechanistic complexities that link a mistimed body clock to mental health.
Mood & Anxiety Disorders
Depression and bipolar disorder display some of the clearest rhythm abnormalities. Flatter actigraphy circadian rhythms were associated with increased risk of major depressive disorder, bipolar disorder, and greater mood instability.² Genome‑wide association studies link clock‑gene variants to bipolar disorder.³ This implies that a built‑in vulnerability in genes that govern circadian rhythms contributes to an increased risk of mood disorders. In a forced‑desynchrony experiment that pushed people to live out of sync with their internal clock, mood and well‑being fell sharply within just four days. The findings show that disrupting circadian alignment alone, independent of outside stressors, is enough to drive depressive symptoms.⁴
Psychotic Disorders
Schizophrenia is often accompanied by strikingly disordered clocks. Up to 80 % of patients show disrupted sleep–wake cycles.⁵ Mounting evidence links schizophrenia to a faulty master clock: mutations in core genes such as CLOCK and disruptions in dopamine‑ and adenosine‑driven timing systems derail both circadian and homeostatic sleep controls.⁶ Genetic, metabolic, and clinical data all support the idea that circadian instability is more than a symptom; it may modulate the dopamine circuitry that is central to psychosis.
Neurocognitive Disorders
Alzheimer’s research now shows that years before memory slips, the body’s 24‑hour clock is already off‑beat: sleep becomes fragmented, melatonin production dips, and daily activity rhythms flatten.⁷ This disruption exacerbates every major Alzheimer’s pathway, accelerating amyloid‑β and tau build‑up, stoking oxidative stress and neuroinflammation, starving neurons of blood flow, and even impairing the brain’s glymphatic “night shift” that clears toxins while we sleep. Damage runs both ways: loss of suprachiasmatic‑nucleus neurons, cholinergic circuitry, and light‑sensing retinal cells further desynchronises the clock, creating a vicious cycle of neurodegeneration. Yet that very feedback loop is a therapeutic opening. Regular bright‑morning light, strict schedules, and chronobiotic aids can realign rhythms, improve sleep, and may slow cognitive decline. In short, protecting your internal clock is emerging as one of the most actionable defences against Alzheimer’s Disease.
Trauma‑ and Stressor‑Related Disorders
Evidence increasingly points to deep circadian ties in post‑traumatic stress disorder (PTSD). When trauma keeps the brain’s “fight‑or‑flight” machinery locked in overdrive, the hypothalamic–pituitary–adrenal axis eventually grows numb: many PTSD patients show a blunted morning cortisol surge.⁸ Because cortisol normally follows a precise 24‑hour script set by the suprachiasmatic nucleus, this flattening signals a core circadian disruption that ripples outward, skewing peripheral clocks across the body. In short, PTSD is both a product and a perpetuator of a body clock driven off beat.
Neurodevelopmental Disorders
Mounting evidence now ties neurodevelopmental disorders (such as autism spectrum disorder and ADHD) to fundamental clock problems. Patients commonly show irregular sleep–wake cycles and atypical melatonin patterns, and animal models replicate these rhythm defects, arguing that circadian dysfunction is baked into the biology of these conditions.⁹ Environmental or genetic disturbances that knock the clock off‑beat can trigger the very behavioural changes seen clinically, while several frontline psychiatric medications further nudge the circadian system. Emerging work suggests that chronotherapy, such as timing light to the body clock, could mitigate symptoms and medication side‑effects, underscoring circadian dysregulation as a core, actionable feature of neurodevelopmental disorders.
Across disorders that seem worlds apart, one truth stands out: when the body’s master clock drifts, the mind follows. That insight isn’t merely academic; it’s a call to act. Light, movement, meals, and sleep are everyday levers we can pull to keep our internal rhythm steady. Guard your circadian rhythms, and you reinforce the very foundation on which mental health is built.
Dr Jonathan Moustakis
Co‑Founder & CTO, Lume Health
References:
Walker WH 2nd, Walton JC, DeVries AC, Nelson RJ. Circadian rhythm disruption and mental health. Transl Psychiatry. 2020;10(1):28. Published 2020 Jan 23. doi:10.1038/s41398-020-0694-0
Lyall LM, Wyse CA, Graham N, et al. Association of disrupted circadian rhythmicity with mood disorders, subjective wellbeing, and cognitive function: a cross-sectional study of 91 105 participants from the UK Biobank. Lancet Psychiatry. 2018;5(6):507-514. doi:10.1016/S2215-0366(18)30139-1
Shi J, Wittke-Thompson JK, Badner JA, et al. Clock genes may influence bipolar disorder susceptibility and dysfunctional circadian rhythm. Am J Med Genet B Neuropsychiatr Genet. 2008;147B(7):1047-1055. doi:10.1002/ajmg.b.30714
Chellappa SL, Morris CJ, Scheer FAJL. Circadian misalignment increases mood vulnerability in simulated shift work. Sci Rep. 2020;10(1):18614. Published 2020 Oct 29. doi:10.1038/s41598-020-75245-9
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Boiko DI, Chopra H, Bilal M, et al. Schizophrenia and disruption of circadian rhythms: An overview of genetic, metabolic and clinical signs. Schizophr Res. 2024;264:58-70. doi:10.1016/j.schres.2023.12.002
Ahmad F, Sachdeva P, Sarkar J, Izhaar R. Circadian dysfunction and Alzheimer's disease - An updated review. Aging Med (Milton). 2022;6(1):71-81. Published 2022 Aug 15. doi:10.1002/agm2.12221
Pan X, Wang Z, Wu X, Wen SW, Liu A. Salivary cortisol in post-traumatic stress disorder: a systematic review and meta-analysis. BMC Psychiatry. 2018;18(1):324. Published 2018 Oct 5. doi:10.1186/s12888-018-1910-9
Bouteldja AA, Penichet D, Srivastava LK, Cermakian N. The circadian system: A neglected player in neurodevelopmental disorders. Eur J Neurosci. 2024;60(2):3858-3890. doi:10.1111/ejn.16423
