Our body operates in two shifts. Wakefulness during sunrise to sunset. Rest during sunset to sunrise. Body functions are organized according to this system. Picture below shows 24 hour cycle in a human who is not exposed to artificial lighting. This cycle has evolved over millions of years and has become a basis for our body to operate every activity.
Before electricity was discovered, all the creatures were exposed to a natural cycle of light and dark of approximately 12 hours. The body had evolved to work in the day and rest in the night. Sunrise and sunset were signals for the shifting in the internal clocks of the body.
During entire day, there was continuous exposure to light. During entire night there was complete darkness (or very little lighting due to traditional lamps). There was never artificial bright light.
Before electricity, man had biphasic sleeping pattern. This comprised sleeping for 4-5 hours and getting up around midnight and again going for a second sleep of 4-5 hours till sunrise.
Electricity introduced many factors that disturbed the body's day and night cycle. Some important changes due to electricity that lead to these consequences are:
Exposure to artificial light, screens, smartphones after sunset.
Frequent changes in work shift. This means exposure to light all night in addition to sunlight in the day.
Jet lag due to long distance air travel. This means change in routine of exposure to light/dark cycle. Body adjusts to this, but in case of frequent jet lags, circadian rhythm is disrupted.
Frequent changes in bed time. This is due to travels, television, smartphone, eating out etc. This has become a norm now a days.
Lack of exposure to sunlight even during day due to closed workspace, not getting out etc.
Continuous exposure to outdoor lighting, street lights, indoor lighting during night.
These changes have disrupted the sleep/wake cycle thereby affecting the circadian rhythm. Tribals residing in forests are least affected by all this.
By dissociating from the urban spaces and modern lifestyle, we have escaped from most of the factors that affect circadian rhythm. For instance, we don’t work at night, do not have a television, do not use smartphone extensively, and don’t have bright lighting in or around home at night, and stay outdoor in day time and so on. We have experienced a tremendous shift in the way our bodies feel. We feel very relaxed and peaceful. Sleep quality has become extremely good. Off course, health has improved a lot. We had realized the hazards of artificial lighting few years ago and took many tiny steps to overcome this risk. Moving to a farm was a major step in this direction.
Common symptoms of affected circadian rhythm include:
Consistent difficulty falling asleep, staying asleep, or both.
Excessive daytime sleepiness or sleepiness during shift work.
Fatigue and exhaustion.
Lethargy.
Decreased alertness and difficulty concentrating.
Impaired judgment and trouble controlling mood and emotions.
Alteration in sexual desire, or appetite, inability to experience pleasure, slowing of speech or actions, crying, suicidal thoughts, job dissatisfaction, addictions, dementia, memory loss, anxiety, bipolar disorder, schizophrenia etc.
Aches and pains, including headaches.
Stomach problems.
Frequent infections, inability to heal etc.
Here, I have listed the human diseases that have been linked with disturbed circadian rhythm due to exposure to artificial lighting, night shift work, jet lag, screen light exposure (smartphone & television), lighting at night, outdoor lighting etc. First, sleep is disturbed, then body rhythm is affected, and this is followed by serious diseases.
When you click the name of the disease, it opens a link to the list of all the scientific studies done on humans, and published in medical journals. The evidence is huge. Each of the studies can be further explored in detail by clicking the links in the study.
To avoid these health hazards, it is essential to understand the body's natural rhythmicity, and respect it. It is simple, work at day (not overwork) and rest at night. Bring back the sunlight & activity in your days, and darkness & sleep in your nights.
Take Care
Madhukar Dama