Photo: Ricky Esquivel/Pexels
If you feel sadder as the days get shorter, you are not alone. About half of the population report feeling less happy in winter and 5 percent fall into serious depression.
Besides nutrition and exercise, having more light in your eyes is the best treatment we know for seasonal mood challenges, says New Zealand-born neurobiology researcher Anna Wirz-Justice, based in Basel, Switzerland. where she is professor emeritus of psychiatric neurobiology. at the Chronobiology Center.
“Clinical studies that have used light as therapy have shown that it is a very powerful treatment,” he tells Susie Ferguson on Saturday morning.
We don’t yet know why some people are more vulnerable to seasonal mood changes, Wirz-Justice says, but it may be related to serotonin levels and vulnerability to depression in general.
The psychological condition known as seasonal affective disorder or SAD is found around the world, but the latitude of where you live may increase your risk.
As New Zealand is a “long and thin” country, the amount of daylight on offer in winter varies greatly, says Wirz-Justice.
Those living in the “mid-latitudes” – including Wellington and Christchurch – are particularly vulnerable to stooping as daylight decreases.
For the large number of people prone to falling into the “winter blues,” more exposure to sunlight may be all that’s needed to keep depression at bay, he says.
“Light, and particularly daylight, which we often don’t access as much as we should, is very important for our basic health, for our psychological health and for our physical health.”
Professor Anna Wirz-Justicia.
Photo: The Daylight Prize
For the 5 percent of those who experience “major depressive disorder” each fall and winter that disappears spontaneously in spring and summer, the therapeutic use of bright artificial light is the best treatment we currently have, Wirz-Justice says.
Sitting in front of the bright light of a special light box for half an hour a day, preferably in the morning, can be effective in lifting these people’s spirits, he says.
These light boxes have an intensity of about 5,000 to 10,000 LUX (a measurement of light on a surface), says Wirz-Justice, which is equivalent to the light of “a bright, sunny day early in the morning.”
Indoors, the intensity of light we are exposed to (typically between 50 and 500 LUX) is not strong enough to stabilize our biological clocks, he says.
Outside, even on a gray, rainy day, the light is much brighter.
To keep the winter blues at bay, Wirz-Justice recommends that people go outside for half an hour every day, preferably in the morning.
Outdoors, you’ll get at least 3,000 LUX, he says, which is enough to synchronize your body clock during the day.
Since the positive effects of light on our biological rhythms occur through eye contact, it is best not to wear sunglasses during this morning light session.
“We’re not talking about light on the skin. We’re talking about light that reaches the retina and goes directly to the brain to affect cognition, mood, rhythms and sleep, and all of that passes through the eyes” .
Exploring the vast potential of sunlight for human and planetary well-being is the goal of Daylight Academy, a group of researchers, scientists and designers of which Wirz-Justice is a part.
Increasingly, hospitals are being designed with interior lighting in mind, he says, and dementia care facilities with lighting systems that artificially signal dawn and dusk.
“The ramifications of what we know about how light affects human behavior, physiology and psychology are growing and enormous.”
