In the era of working from home due to COVID-19, many of us may be spending significantly more time indoors staring at bright screens. As we attend online meetings and scroll through social media, we’re exposed to more artificial light than our bodies are accustomed to. Doctors have been studying the relationship between light and human health, and our growing exposure to artificial light may only be exacerbating the impact.
The relationship between light exposure and human health
In a recent presentation, Helen Burgess, Ph.D., professor of psychiatry and co-director of Michigan Medicine's Sleep and Circadian Research Laboratory, shared context on the relationship between light exposure and human health, along with recent research on light treatment.
Burgess is an expert on the circadian effects of light on the human body, with years of research experience in sleep and its relationship to light. She discusses how it affects our body’s central circadian clock and the natural ‘circadian rhythm’ process that follows a daily cycle and typically responds to ambient light.
“We know in humans, on average, the endogenous period, or the time it takes for the central clock to complete a cycle, is a little over 24 hours,” Burgess explains.
As a result of this extra time, studies have shown that people's internal clocks often tend to drift later in the day if they're not exposed to regular cues to tell them what time it is. To correct this, Burgess says we need "phase advancement," or waking up earlier than our bodies naturally would without any external cues, to stay in sync with the Earth's 24-hour day.
This is where light, the most powerful environmental cue on the circadian clock, comes in. Burgess says that morning light has a strong effect for most people.
Evening light
“We have reduced sensitivity to light in the middle of the day … and we are much more sensitive to light around the time that we normally sleep,” Burgess explains. “For many of us who have to shift earlier, morning light is actually the most important light that we get during the day. On the other hand, evening light, the light before bed and during the sleep period, is going to delay your phase. This is going to reinforce the natural tendency to shift later that many of us have.”
This evening light can be extremely prevalent in the era of COVID-19, as many people tend to stay home in the evenings and consume entertainment through brightly lit screens.
While it's tempting to work on your computer or watch TV, it may be best to reduce screen time, as studies have shown that evening light from electronic devices is linked to lower sleep quality and poorer health.
Evening light has been shown to suppress melatonin, which Burgess says can become a health problem over time. “We know that lower baseline melatonin levels are predictive of developing several diseases over several years,” she explains, including potentially breast cancer, hypertension and type 2 diabetes.
On the other hand, morning light treatment can do wonders for depression, mood and overall health, Burgess says.
“We find that morning light treatment is an effective antidepressant, as effective as a pharmaceutical antidepressant,” she explains. This form of treatment tends to have fewer side effects than medications and may be linked to increased serotonin levels in the brain, which can regulate mood and happiness.
Source: www.healthblog.uofmhealth.org
To share: