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In a number of mental health conditions, an overlap of different pathophysiological factors (so called p factors) is commonly observed, one of which is impaired sleep. The disruption of circadian rhythms in different mental health disorders, which can manifest as having trouble falling asleep, waking up several times a night and not being able to go back to sleep, or waking up too early has been discussed in a recent review article by Alachkar and co-authors, published in the journal Translational Psychiatry.

If you are a reader of the MGC blog, you probably already know that the term “circadian rhythm” refers to the regular fluctuations (“oscillations”) of hormones, neurotransmitters, and biochemical processes synchronized with the 24-hour day and night cycle. Factors that impact circadian rhythmicity are the light that enters the eyes, as well as the timing and type of food that is consumed. Cognitive function, mental health, and well-being, as well as neurodevelopment are highly dependent on circadian rhythmicity, and loss of synchrony of hormonal fluctuations are associated with mental health issues, as well as impaired neurodevelopment in children.

Interestingly, circadian rhythm disruption during pregnancy as well as early childhood have been shown to predispose children to being at higher risk for developing Attention Deficit Hyperactivity Disorder, Autism Spectrum Disorder and Tourette’s syndrome. These behavioral manifestations are attributed to a disruption in interactions between the circadian Clock system and the Hypothalamic Pituitary Adrenal (HPA) axis, both of which are important for tuning behavior and physiology to the sleep-wake cycle. This tuning is mediated by the secretion of hormones responsible for wakefulness (cortisol) or drowsiness (melatonin). Circadian disruption due to prenatal or early life stressors may cause hyperactivity of the HPA axis, which has long been associated with ASD, ADHD, and other neurodevelopmental disorders.

Based on a number of preclinical and clinical studies, a disruption of circadian rhythms has been found to be shared amongst several clinical disorders including depression, anxiety, eating disorders, bipolar disorder, schizophrenia, as well as Parkinson’s and Alzheimer’s disease. Across many different clinical studies, the majority of patients with psychiatric disorders reported some sort of sleep disruption as a symptom or precursor of the condition. Importantly, converging evidence suggests that there exists a complete circular relationship between circadian rhythm disruption and stress, in which stress provokes disrupted sleep, and the sleep disruption in turn contributes to higher stress. Considering the interconnectedness between circadian neurophysiology and the HPA axis discussed before, this association may explain why circadian rhythm disruption is considered a p factor across a spectrum of mental health disorders.

Based on these insights, it appears critical to develop good sleep hygiene to prevent or counteract the development of mental health conditions. Due to the direct interdependence of sleep quality and stress, it is important to maintain or reestablish a healthy balance of cortisol fluctuations to help favor good sleep. This can be achieved through lowering psychological stress for example by processing emotional wounds and trauma through talking or writing about it, lowering dietary stress by making gut health supporting dietary choices, as well as striking a balance between activation of the sympathetic and parasympathetic nervous system by engaging in mindfulness practices such as meditation or yoga on a regular basis.

On the other hand, lowering stress through improved sleep can be attempted by adopting some sort of time-restricted eating schedule, such as the 16/8hr schedule in which there is a 16hr period without food intake (including the sleeping hours) alternating with an 8-hour window of food ingestion. Furthermore, getting blue light exposure by going outside or working by a window, especially in morning hours, as well as avoiding any sort of blue light exposure in the evening by reducing screen time or using screens and lamps with warm light will help normalize circadian rhythms and promote improved sleep.