The midnight sun is a phenomenon that occurs in certain places in the Northern Hemisphere such as Iceland or Alaska. During the summer months, the sun never sets or barely sets, resulting in constant daylight. Many people in these locations invest in blackout shades and sleep with eye masks on in order to reduce the amount of light while they are trying to sleep at night. Many people are extremely fond of this prolonged period of light, as it gives them more time to do various outdoor activities and enjoy their summer. However, could the constant light have an adverse effect on the overall health of the people who experience it?
Light and brightness play a major role in humans' regulation of energy, mood, and sleep. Melatonin, the hormone that causes the feeling of sleepiness, is produced in the body in response to darkness. It is for this reason that it is recommended to stay off of your phone several hours before bedtime. In the absence of darkness, melatonin release is negatively impacted making it harder to fall asleep (Wilczynski). Our circadian rhythms are accustomed to a typical 24-hour light-dark cycle as the Earth rotates about its axis. As a result of the midnight sun, circadian rhythms become out of sync with the abnormal light-dark cycle.
In his talk, Dr. Fred W. Turek, professor of neurobiology at Northwestern University, explained that circadian desynchrony can have numerous adverse effects on human health. Shift workers have been shown to have an above average risk of developing diabetes, cardiovascular disease, and cancer. Could the midnight sun be having a similar effect on those who experience it? Unfortunately, there is little research in this area regarding the long-term effects of the midnight sun on humans. Various studies have shown than many polar species have adaptations that alter their sleep patterns to adjust to the new light-dark cycle. For example, reindeer rely on their ultradian rhythm during this time meaning they sleep whenever they need to digest their food (Hickok). There are, however, short term implications of the midnight sun on humans if no remedial measures are taken to combat the constant light. Without blackout shades or sleep masks, the brain cannot tell when it is time to sleep because of the light which can make it harder to actually fall asleep. Difficulty sleeping for a prolonged period of time can impact mood and some physiological functions.
Further research is necessary to determine the extent to which circadian rhythms in humans who experience the midnight sun are disrupted and if there are any long term health implications. While people can simulate darkness when they are ready to sleep, there is still an overall disruption in their circadian rhythms. It may also be worth investigating if people whose families have been experiencing the midnight sun for generations have any sort of genetic advantages that make adjustment to the midnight sun any easier.
References:
Hickok, Kimberly. "How does the summer solstice affect animals?" LiveScience, 18 Jun. 2021, https://www.livescience.com/62870-summer-solstice-animals.html.
Wilczynski, Juliana. "Ask A Sleep Scientist: How Does The Midnight Sun In Iceland Affect Sleep?" The Reykjavík Grapevine, 23 Jun. 2018, https://grapevine.is/mag/articles/2018/06/23/ask-a-sleep-scientist-how-does-the-midnight-sun-in-iceland-affect-sleep/.
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