The COVID-19 crisis has created misery, suffering and hardship on a global scale. If there is any silver lining, it might be the renewed appreciation of our fundamental linkage with the physical environment and what that means not just for survival, but for resilience as a species. I write on sleep topics and human behavior and emphasize our basic, culturally universal homeostatic and circadian rhythms linked to the solar day/night.
When we imagine our paleolithic ancestors, in a hunting and gathering society, dwelling within sub-tropical or tropical settings, we picture humans freely roaming the landscape, in search of plants, herbs, nuts and seeds, or protein sources. They were constantly in the clutches of nature, experiencing sunlight and clean air, with green and blue wavelengths emanating from combinations of sky, water and vegetation. A spectrum of sensations accompanied immersion in the physical environment. After a day of keeping a wary eye on potential animal predators or hostile tribes, they returned to shelters, caves or other dens, resting from their wanderings or foraging. Our ancestors experienced growing darkness, perhaps punctuated by a glowing fire. As the evening progressed, and the fire turned to burning embers and coals, the dim light melatonin onset kicked in, and sleep became inevitable.
I suspect our ancient brethren experienced many nights of sound sleep, with the early to bed and owlish chronotypes keeping vigils on overlapping shifts; biphasic sleep periods could have occurred, allowing for socializing, mating and eating in the middle of the night. Natural light energy and reflectivity, uninterrupted by air pollution or artificial environments, on a daily basis, powered the hypothalamic-based suprachiasmatic nucleus (SCN) to generate temporal signals to neuropeptides, neurotransmitters and peripheral organ and tissue activity, regulating emotional, behavioral and metabolic stability.
Light and movement during the day drives our dopaminergic and serotoninergic system, influencing reward-based and affectively modulated behaviors. When the sun set, true darkness enveloped our ancestors, allowing melatonin to be produced by the pineal gland and exerting an influence on the SCN master clock, permitting the initiation of the natural sleep cycle. Ingress and egress points for the shelters provided early morning light entry and facilitated natural awakenings, and suppression of melatonin, without alarm clocks, dawn simulators or coffee pots percolating.
Surrounded by natural background sounds, internal body signals were not as easily ignored or drowned out by the asynchronous chorus of mechanical, human contrivances we find in every corner of our busy lives. One would imagine plenty of physical space for social distancing from the herd. Afternoon heating and glare may have encouraged early humans to seek shade and perhaps take a short, refreshing nap, ready to being the process of gathering for evening meal and tribal affiliation, creating a safe and reliable enclave for the night. The celestial dome was routinely darker to a much greater extent than in today’s night sky. Even low levels of extraneous light during the sleep period can impact melatonin and sleep depth as well as continuity.
One of the emerging lessons of this pandemic is that appropriately distanced outdoor activity provides a margin of safety from viral infection that is less guaranteed in crowded indoor spaces involving community gatherings. Among educational experts there is discussion and planning around children schooling in outdoor tents, engaged in experiential learning and connecting with nature. Their intrinsic curiosity is satisfied by the unpredictable, spontaneous and wondrous events that unfold in our natural surroundings. Our so-called civilized society crams individuals into crowded, ersatz spaces for work, school or play (classrooms, bars, sporting arenas, cinemas) with constant artificial illumination. The wisdom and dictates of pandemic management compel us to re-balance our priorities and choices.
In the face of the gaping maw of COVID-19, nature is telling us loudly and clearly how we can facilitate our adjustment to this contagion.
Dr. Michael V. DeSanctis, PhD, LP, ABPP, DBSM
Licensed Psychologist; Diplomate Board of Behavioral Sleep Medicine