Would Permanent Daylight Saving Time Prevent Depression?

Regionalizing a time change to reverse seasonal affective disorder.

Posted Oct 05, 2017

Several days ago, Boston newspapers reported that Massachusetts is considering staying on Daylight Saving Time permanently. Doing so would move the state into the Atlantic Time Zone. The decision depends on the responses of other New England states, and even New York state. Were this switch to occur, we would be balancing the advantages of a later sunset to the disadvantage of prolonged morning darkness. Delaying the start of the school day so children would not have to travel in the dark is already being discussed if the proposal goes through. However, the benefits of a delayed sunset are compelling, according to one proponent of the plan. Darkness would not arrive by 4 p.m., or even earlier as it does now during the shortest days of the year. People would supposedly engage in after-work activities and possibly bring more business to restaurants, stores, and entertainment venues because of the delayed darkness.  

One advantage not mentioned in the proposal was eliminating the brief but annoying adjustment everyone has to make when we move the clock an hour backward in the fall and then one hour forward in the spring. This seems to cause national jet lag, and while many people feel sleepy and disoriented for a couple of days, some are plunged into unwelcome periods of anxiety and depression because of the shift in time. Mental health professionals are well aware of the intensification of mood disorders in the weeks following the switch in time.

Late fall and winter darkness in the northern hemisphere and its opposite in the southern hemisphere are now known to have a well-characterized impact on mood, energy, sociability, sleep, and weight. The most extreme examples come from personal accounts and studies of people living in research stations in Antarctica, when weeks of total darkness can exert a devastating toll on people’s emotional well-being. But one does not have to move to the bottom of the world to experience the deterioration in mood brought about by a significant reduction in light. Studies on seasonal changes in mood among people who move from a lower latitude to a country with a higher one (e.g., from Japan to England), have found a higher rate of depression among those who moved to the seasonally darker country than their compatriots back home. Many in our country who live in the northern tier of states seek out winter vacations or longer seasonal residences in the southern states to bring relief not just from miserable weather, but from miserable moods as well. And when those who made the migration south permanent talk about never "going back north" because of the winter cold, they may also recoil against ever again experiencing winter depression.

But there are many places in the world in addition to the tips of the globe where daylight is missing entirely for two or three months of the year, and the remedy for the severe seasonal mood changes is not moving the clock ahead or behind, or keeping it the same. One such place is Tromso, Norway, a tiny island similar in size as Manhattan. It is north of the Arctic Circle and has a population of about 70,000. A few years ago, a then-graduate student at Stanford, Kari Leibowitz moved to this very northerly city to study the mental attitudes and moods of a population unable to escape the total darkness of late fall and early winter. Using a test she developed to measure the attitudes of the residents toward winter, the “Wintertime Mindset Scale,” she asked the residents about their view of winter. For example, do they disagree or agree with a statement that, “They enjoy many things about the winter’ or ‘They find winter months dark and depressing.” This second question would probably have many New Englanders' answering, “Yes, I agree,” but not so with the Norwegians. The consensus among the inhabitants was that they found the winter agreeable because it had the right combination of winter outside activities and inside coziness. Despite the severe cold, they claimed that only inadequate clothing, not temperature, caused discomfort.

It is possible of course that inhabitants, the ones who still live there, are pre-selected for their happy tolerance of the winter. Those who found the winters intolerably depressing may have moved to southern Italy or Ecuador, and never put on snow boots again. But it could also be that the logistical discomforts of winter: poorly plowed roads, unshoveled sidewalks, clothing not warm enough for outside yet stiflingly warm when inside a store or supermarket, lack of time and money to engage in outside winter sports, high heating bills, and canceled events due to snow emergencies…to name a few New England cultural gripes? These are not problems the people of Tromso experience. 

Staying on daylight saving time may give people an opportunity to engage in outside activities after work, and develop a Tromso mindset toward winter. But it comes with a mental health risk that may not be adequately evaluated by the proponents of this change in time. The increased hour of darkness in the morning resulting from not switching to Standard Time may potentiate symptoms of a winter depression or seasonal affective disorder. In fact, early morning exposure to a light source that mimics sunlight has been a standard therapy for years, and sitting in front of a ‘sunbox’ for a half an hour or so effectively improves mood within a couple of days. Are we risking the mental health of our residents by moving that hour of light from the morning to the afternoon? Or can we compensate for the lack of morning light by using artificial sunlight in our schools and places of employment? Then we might come close to, ‘burning the candle at both ends.'