Blue light exposure at night can disrupt the mother’s circadian rhythm — a factor increasingly linked to fetal development and autism spectrum disorders.

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A Neglected Risk Factor in Pregnancy

Adverse pregnancy outcomes are commonly linked to factors such as poor nutrition, stress, and environmental toxins. Circadian disruption is now being recognized as another important contributor. Research over the past decade indicates that the circadian system begins developing prenatally through entrainment from the mother.

—Circadian Rhythms as Modulators of Brain Health During Development and Throughout Aging, PMC

How the Fetal Clock Develops — and Why It Matters

The foundation of the circadian system begins forming well before birth. In humans, the brain’s master clock—known as the suprachiasmatic nucleus (SCN)—can be identified by the third trimester. This system is thought to develop in response to maternal signals such as melatonin and daily light-dark cycles. A baby is believed to have a fully functional SCN by around nine months of age.

Research indicates that circadian rhythms influence brain development from early gestation through old age. Disruptions during prenatal development may increase the risk of behavioral and cognitive impairments later in life, while aging is also associated with a natural weakening of these rhythms. Supporting a strong internal clock during pregnancy may therefore be one of the simplest, yet most powerful ways to help protect long-term brain health.
— Circadian Rhythms as Modulators of Brain Health During Development and Throughout Aging, PMC

How Circadian Disruption Occurs in Pregnancy

Epidemiological studies have revealed associations between gestational chronodisruption and adverse pregnancy outcomes. Common sources of circadian disruption during pregnancy include:

• Shift work
  
• Jet lag from travel across time zones
  
• Exposure to artificial light at night
  

— Light and Circadian Signaling Pathway in Pregnancy: Programming of Adult Health and Disease

A Link Worth Investigating Further

The connection between Autism, Circadian Disruption and Pregnancy is becoming more evident as researchers explore how maternal circadian health may shape neurodevelopmental outcomes in the fetus.

Epigenetic Impacts: Altered Placental DNA Methylation

Early-life circadian disruption may increase the risk of chronic illness later in life. Circadian rhythms regulate critical biological processes, including hormone secretion and metabolic function. When disrupted—such as through night shift work—these rhythms can influence the developing fetus in unexpected ways.

One emerging area of concern is the impact on placental DNA methylation.

Clarkson-Townsend et al. (2019) conducted the first study to examine how night shift work, used as a proxy for circadian disruption, may alter methylation patterns in the placenta. Although the findings require cautious interpretation, the study suggests that maternal circadian disruption could lead to epigenetic changes with lasting effects.

Animal studies also indicate that circadian desynchrony in early life can lead to enduring autistic-like behavioral changes in adulthood, reinforcing the potential long-term impact of disrupted rhythms during gestation.

Autism Spectrum Disorders and Neurodevelopment

Autism spectrum disorders include social, communication, and behavioral challenges. Among these are Asperger’s Syndrome and Childhood Disintegrative Disorder. ADHD and autism are both neurodevelopmental conditions that affect brain development and how a person functions day to day. Symptoms typically appear in early childhood and can influence behavior, learning, communication, and emotional regulation throughout life.
— ADHD vs. Autism: The Differences and Similarities

Practical Guidance for Expectant Mothers

Given the potential risks, gynecologists and healthcare professionals should advise pregnant women—and those planning to conceive—to minimize exposure to artificial light at night, especially blue light emitted by phones and screens. Limiting screen use at night is a simple, cost-free measure that may help safeguard fetal circadian development and support healthier neurodevelopmental outcomes.
More on the topic

Dramatically altered environmental lighting conditions in women with high-risk pregnancy during hospitalization – EMFSA

The Emerging Link between Wireless and Autism – EMFSA

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In this newsletter, we explore the rising rates of colorectal cancer among young people. Be sure to read ‘An Illustration of Modern Life,’ which provides a glimpse into the life of a child in today’s world

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Abstract

Insufficient sleep and mistimed sleep are prominent, yet under-appreciated and understudied, contributors to poor mental health and to mental disorders. The evidence that improving sleep and circadian functioning is an important pathway to mental health continues to mount. The goal of this paper is to highlight three major challenges ahead. Challenge 1 points to the possibility that comorbidity is the norm not the exception for the sleep and circadian disorders that are associated with mental disorders. Hence, the sleep and circadian problems experienced by people diagnosed with a mental disorder may not fit into the neat diagnostic categories of existing nosologies nor be adequately treated with single disorder approaches. The Sleep Health Framework and the Transdiagnostic Intervention for Sleep and Circadian Dysfunction (TranS-C) are discussed as alternative approaches. Challenge 2 points to the large time lag between the development of a treatment and the availability of that treatment in routine clinical practice. This is a key reason for the emergence of implementation science, which is a flourishing, well-developed, and quickly moving field. There is an urgent need for more applications of implementation science within sleep and circadian science. Challenge 3 describes one of the greatest puzzles of our time—the need to unlock the fundamental elements of behavior change. There is potential to harness the science of behavior change to encourage widespread engagement in sleep health behavior and thereby reduce the staggering burden of sleep and circadian problems and the associated mental health problems.

The post Treating sleep and circadian problems to promote mental health: perspectives on comorbidity, implementation science and behavior change appeared first on EMFSA.

Abstract

The circadian clock is an evolutionarily highly conserved endogenous timing program that structures physiology and behavior according to the time of day. Disruption of circadian rhythms is associated with many common pathologies. The emerging field of circadian medicine aims to exploit the mechanisms of circadian physiology and clock–disease interaction for clinical diagnosis, treatment, and prevention. In this Essay, we outline the principle approaches of circadian medicine, highlight the development of the field in selected areas, and point out open questions and challenges. Circadian medicine has unambiguous health benefits over standard care but is rarely utilized. It is time for clock biology to become an integrated part of translational research.

https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001567

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The publisher’s final edited version of this article is available at Science

Abstract

Circadian clocks temporally coordinate physiology and align it with geophysical time, enabling diverse lifeforms to anticipate daily environmental cycles. In complex organisms, clock function originates from the molecular oscillator within each cell and builds upwards anatomically into an organism-wide system. Recent advances have transformed our understanding of how clocks are connected to achieve coherence across tissues. Circadian misalignment, often imposed in modern society, disrupts coordination among clocks and has been linked to diseases from metabolic syndrome to cancer. Thus, uncovering the physiological circuits whereby biological clocks achieve coherence will inform on both challenges and opportunities in human health.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8123919/

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Abstract

Daily rhythms of behavior and neurophysiology are integral to the circadian clocks of all animals. Examples of circadian clock regulation in the human brain include daily rhythms in sleep-wake, cognitive function, olfactory sensitivity, and risk for ischemic stroke, all of which overlap with symptoms displayed by many COVID-19 patients. Motivated by the relatively unexplored, yet pervasive, overlap between circadian functions and COVID-19 neurological symptoms, this perspective piece uses daily variations in the sense of smell and the timing of sleep and wakefulness as illustrative examples. We propose that time-stamping clinical data and testing may expand and refine diagnosis and treatment of COVID-19.

https://journals.sagepub.com/doi/10.1177/07487304211031206

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Abstract 

Chronobiology is the scientific discipline which considers biological phenomena in relation to time, which assumes itself biological identity. Many physiological processes are cyclically regulated by intrinsic clocks and many pathological events show a circadian time-related occurrence. Even the pituitary–thyroid axis is under the control of a central clock, and the hormones of the pituitary–thyroid axis exhibit circadian, ultradian and circannual rhythmicity. This review, after describing briefly the essential principles of chronobiology, will be focused on the results of personal experiences and of other studies on this issue, paying particular attention to those regarding the thyroid implications, appearing in the literature as reviews, metanalyses, original and observational studies until 28 February 2021 and acquired from two databases (Scopus and PubMed). The first input to biological rhythms is given by a central clock located in the suprachiasmatic nucleus (SCN), which dictates the timing from its hypothalamic site to satellite clocks that contribute in a hierarchical way to regulate the physiological rhythmicity. Disruption of the rhythmic organization can favor the onset of important disorders, including thyroid diseases. Several studies on the interrelationship between thyroid function and circadian rhythmicity demonstrated that thyroid dysfunctions may affect negatively circadian organization, disrupting TSH rhythm. Conversely, alterations of clock machinery may cause important perturbations at the cellular level, which may favor thyroid dysfunctions and also cancer.

Excerpt

Introduction

From ancient hourglasses to sophisticated modern clocks, the measurement of time has been considered indispensable by man for the verification of the flow of natural and human phenomena. The earliest recorded recognition of the importance of biological rhythms in plants and animal dates back to at least 5000 BC. Light/darkness-correlated variations in leaf movements in some plants had been already observed by Androstene during the Empire of Alexander the Great, and the importance of temporal factors was even recognized in biblical times as stated in Ecclesiastes: “To everything there is a season and a time to every purpose under Heaven: a time to be born and a time to die; a time to plant and a time to harvest”. Moreover, as reported in Genesis, the light was created by God first of all, and this is of particular significance, since, as we will see later on, the alternation of light/darkness is the main synchronizing factor in the circadian rhythm [1]

5. Conclusions

Knowledge and respect of biological rhythms and of their endogenous and environmental synchronizing factors is mandatory not only for physicians but also for patients, to ensure the best conditions for the lives of human beings. This is particularly important for the HPT axis, as the knowledge and respect of the reciprocal relationship between the secretions of this axis and the circadian machinery may avoid, on the one hand, the disruption of the circadian rhythmic organization of the subjects and, on the other hand, the consequences of this disruption, which can cause not only thyroid dysfunction but also thyroid cancer. Further studies have to be encouraged to better clarify physiological and pathophysiological aspects of this issue and to search for more appropriate preventive choices to avoid circadian but also ultradian and infradian rhythm disruption of the HPT axis and to search for more effective therapeutic options to promptly correct these alterations, when they have already occurred.

https://www.mdpi.com/2075-1729/11/5/426

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