(Newswire.net— May 30, 2020) — For the last two months, a good part of the world’s population was forced to spend time locked up in their homes, going out only for the most basic groceries. While this may have reduced our chances of exposure to the coronavirus, it may have had a less obvious effect on our immunity by making us more vulnerable to other infections, writes Linda Geddes for the BBC Future.
Vitamin D
Humans evolved to become accustomed to the 24-hour cycle of light and darkness, and our bodies are set up to work in conjunction with sunlight. One of the most obvious examples of this is the production of vitamin D in the skin in response to UVB exposure. This daily dose of vitamin D can help strengthen our bones and teeth, but it also has an effect on our immune cells.
Vitamin D allows macrophage in our lungs – the first line of defense against respiratory infections – to release an antimicrobial peptide called cathelicidin, which directly kills bacteria and viruses. It also adjusts the activity of other immune cells, such as B and T, which trigger longer-term reactions. People with low levels of vitamin D are more at risk of viral infections of the respiratory tract such as influenza.
Exercise
Although there is no specific data to prove that regular exercise makes us less likely to getting COVID-19, various studies have suggested that working out boosts our defenses against other viral infections, including influenza and the common cold, as well as improving the immune response to vaccination.
One explanation for these benefits is stress reduction. People use exercise as a stress buffer, and it’s very obvious that high levels of chronic stress aren’t good for the immunity, said Neil Walsh, who studies the effects of exercise on the immune system at Liverpool’s John Moores University in the UK.
Socializing
Being outdoors has many benefits in addition to more exercise and vitamin D, and various theories have tried to explain these findings. One is that time spent outside can help combat stress and loneliness by bringing us into contact with other people. And then there’s the Theory of Recovery, which suggests that natural patterns and movement easily engage our attention, giving our tense brains a chance to rest and recover.
Time spent near trees
It is also possible, however, that trees affect our immune systems more directly – several studies have suggested that a few days spent in the woods lead to an increase in the number and activity of the natural killer cells in our blood – immune cells that help find and destroy viruses and cancer cells. Scientists in Japan have suggested that inhaling particles called phytoncides, which are released by trees, could be a contributing factor to this. They have been shown to alter the activity of human natural killer cells when grown outside the body, although much more work is needed to confirm whether their inhalation has a similar effect.
Internal clock
The time we spend indoors during isolation could disrupt our circadian rhythm – an internally generated nearly perfect 24-hour cycle in the activities of numerous biological processes, including sleep. Our circadian rhythm is usually in sync with or in tune with the period of the day we spend outside through the activity of bright light that affects a group of light-sensitive cells at the back of the eye. These eye cells communicate with a part of the brain called the suprachiasmatic nucleus, which functions as the main clock in our body.