For 3.5 billion years, life has evolved around the sun; and the importance in the animal kingdom is glaringly apparent. You only have to look to nature to see how changes in light throughout the day alter behaviours out in the wild. For example, some animals have evolved to be more sensitive to sound and need very little light to find their way around and hunt their prey. At the same time, others rely on sunlight for vision and alertness, with humans like yourself falling into that category, suggesting that changes in exposure to natural light are going to have an impact on your health and behaviour over a life span.
Wind forward a few billion years to when electrical light became widely available in the 1930s. How much has this affected our internal clocks, which signals our bodies when to prepare for sleep and wakefulness?
With the ability to now flip a switch and flood a room with bright it led to exposure to light much later into the night than would not be possible out in nature. Add that to a culture of being on the phone screen or watching TV until 10 pm and late nights drinking at the weekend, and it’s bound to wreak havoc and cause disruptions in sleep and health due to changes in the circadian rhythm.
It’s now 2021; you wake up in a bed to the sound of an alarm. It’s dark. You skip breakfast to spend a few more moments in bed and drive to the office to spend your time under electrical lights, sitting all day in front of a monitor beaming with blue light to arrive home around 6 pm, cook dinner and eat at the table whilst it’s dark outside having hardly seen any natural daylight. This schedule is typical in modern life, especially for those in the city or countries with short winter days. For many, they barely get 15 minutes of natural light exposure. Given that sunlight in our universe’s life force, the lack of exposure to the sun undoubtedly plays a role in our chronic disease-ridden society.
Imagine if only we could reset the body clock?
Perhaps escaping away from the rat race to get back into touch with nature, to shift our rhythm back into sync a few times a year – would that be beneficial?
According to a study published in Current Biology (2013), spending just one week exposed only to natural light while camping in the Rocky Mountains was enough to synch the circadian clocks in participants who were left to wake and sleep according to the sun as we would have done all those years ago.
To grasp an understanding of the effects of electrical lighting, a research team at Colorado-Boulder’s Sleep and Chronobiology Laboratory monitored eight participants for one week as they went about their daily lives. The participants wore monitors on their wrists that recorded light exposure and movement activity, allowing the researchers to record when they were sleeping.
At the end of the week, the researchers also recorded the timing of participants’ circadian clocks by measuring the presence of the hormone melatonin. The release of melatonin signals our physiology that it’s nighttime and prepares the mind and body for sleep.
Six men and two women around the age of 30 went camping in Colorado’s Eagles Nest Wilderness. During the week, the campers were exposed only to sunlight and the glow of a campfire. Flashlights and personal electronic devices were not allowed. Following a week of camping, the same metrics were measured.
Compared to the camping period, electrical lights shifted the biological nighttime back by two hours, and, on average most participants woke up earlier before nighttime was over. After the camping trip — where study subjects were exposed to four times the intensity of light compared with their everyday lives — participants’ biological nighttimes began near sunset and ended at sunrise. They also woke up just after their physical night had ended. Becoming in sync with sunset and sunrise happened for all individuals even though the measurements from the previous week indicated that some people were prone to staying up late and others to getting up earlier.
This study indicates that sleep has become much of a social construct and that the idea of night owls and morning larks may well be due to behavioural shifts from the use of electrical lighting and screens. However, as little of spending seven days out in nature is enough to resync the body clock and may well be an appropriate means of therapy for those with sleep or health issues related to alterations in their body clock. Instead of requiring medications with side effects such as sedatives or hormones, people could go away camping for a few nights without spending time on their phones, a much more safe, enjoyable and natural way to improve insomnia and overall health and wellbeing.
- Kenneth P. Wright, Andrew W. McHill, Brian R. Birks, Brandon R. Griffin, Thomas Rusterholz, Evan D. Chinoy. Entrainment of the Human Circadian Clock to the Natural Light-Dark Cycle. Current Biology, 2013; DOI: 10.1016/j.cub.2013.06.039
Martin McPhilimey BSc MSc MRes
Consultant, Coach, Scientist.