What You Need to Know

Artificial Light at Night: What You Need to Know

Written on March 23, 2024 at 10:17 am, by Eric Cressey

Today, I have a guest contribution from Examine.com researcher, Lucas Roldos. This is an adaptation of an Editor’s Pick from Examine (1), and it’s especially timely, as Examine is celebrating their 13th anniversary with some great sales HERE.

The study in question: Artificial light at night suppresses the day-night cardiovascular variability: evidence from humans and rats

The 24-hour light/dark cycle is the most important factor affecting our circadian rhythm. As our exposure to light changes throughout the day, a region of the brain called the “suprachiasmatic nucleus” responds by modifying the release of hormones (like cortisol and melatonin), body temperature, blood pressure, and mental alertness. This physiological responsiveness to light ensures that we are alert and ready to take on the day when the sun is out, and that we are able to rest when the sun is down. However, with the prevalence of artificial light sources like computer screens and light pollution, our bodies may feel like it’s daytime even late at night.

This study (2) was a narrative review that investigated whether exposure to artificial light at night (ALAN) had any negative effects on cardiovascular health or cortisol levels in adults, including night shift workers. The findings of the included studies suggested a correlation between increased ALAN exposure and a heightened risk of high blood pressure, heart rate, autonomic nervous system activity, and carotid artery thickness, along with disrupted cortisol levels and day-night heart rate variability.

While more research is needed to solidify this relationship, it is crucial to consider these results. The implications of excessive ALAN exposure could serve as a strong argument for minimizing exposure to electronic devices like smartphones, computers, and televisions at night. Moreover, the escalating light pollution worldwide raises concerns about its impact on human health. With the Earth’s artificial light area continuously growing, and a considerable portion of the population residing in areas affected by light pollution, recommendations include avoiding high light intensities above 10 lux in the evening, as even basic sources of light pollution, such as streetlamps and car lights, can surpass this threshold.

Data from Brown et al. (2022) (7), Gaston et al. (2013) (8), and Wood et al. (2013). (9)

The impact of ALAN on circadian rhythms, particularly the suppression of melatonin secretion and disruptions in circadian-related gene expression, can have significant effects on various physiological activities. A primary mechanism through which ALAN affects the circadian system is by inhibiting melatonin secretion and downregulating genes involved in circadian-related feedback loops, leading to compromised cardiovascular health and systemic inflammation. Proper alignment with the circadian rhythm through consistent lifestyle habits and behavioral patterns is recommended for overall health improvement, emphasizing the importance of maintaining regular sleep patterns, meal timings, physical activity, and light exposure, despite occasional disruptions.

Adapted from Poggiogalle, Jamshed & Peterson, 2018. (14)

For individuals dealing with cardiovascular issues, managing ALAN exposure is just one component of stress reduction strategies, along with prioritizing quality sleep, avoiding tobacco and alcohol, and integrating exercise, weight management, and dietary adjustments into a comprehensive prevention and treatment plan.

If you found this information valuable, you’ll appreciate the full resources available at Examine.com. Their anniversary sale offers an opportunity to explore cutting-edge research in the health and performance realm.

Note: references for this article are posted as the first comment below.

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