Q: I tend to feel more tired than usual when it’s cloudy or rainy. Why is that?
If you’re feeling tired on an overcast day, it could be for any number of reasons, experts say. Maybe it’s because you’re lounging around at home and not as active as you usually are. Or maybe the change in atmospheric pressure is causing a headache or other aches and pains.
Or perhaps, said Dr. Alfred J. Lewy, a professor emeritus of psychiatry at Oregon Health & Science University, it’s because of something else going on in your body that experts don’t fully understand.
The truth is, scientists don’t know how — or even if — daily weather changes like the occasional overcast day can influence energy levels.
“It’s kind of a mess to study,” said Kelly Rohan, a professor of psychological science and a clinical psychologist at the University of Vermont. And research on the topic is sparse.
Not everyone has the same response to the weather, the experts said. Some people hate the rain or are especially sensitive to a lack of sunlight, while others cannot stand a sweltering summer day.
“We’d love to say there’s an easy answer, but there just isn’t,” said Dr. Paul H. Desan, a psychiatrist and director of the Winter Depression Research Clinic
at the Yale School of Medicine.
The best research has tried to tease out how certain aspects of a day — like the temperature or atmospheric pressure, or how sunny, cloudy or rainy it is — might affect your mood while controlling for other factors like the season and how much time you spent outside. Most of these studies have not measured energy levels alone, Dr. Rohan said, but have assessed mood by asking people questions about how they’re feeling as well as how active or alert they are.
Dr. Rohan’s read on that research, she said, is that for most people, the weather’s influence on day-to-day mood is “either nonexistent or very subtle.”
In a 2010 study of more than 14,000 people in the Netherlands, for example, researchers concluded that weather conditions were not associated with a low mood. And a 2008 study of more than 1,200 people in Germany found that the average effect of weather on mood was small, and that both sunny and rainy days were associated with tiredness.
In general, Dr. Rohan said, your daily stress, such as from relationships or work, is probably going to affect your mood “much more than the weather forecast.”
Fleeting feelings of lethargy should not be confused with seasonal affective disorder, or SAD, the experts said. SAD is a type of depression that affects about 5 percent of adults in the United States — it is more common among women than it is among men and it tends to run in families. Typically, SAD arrives in the fall or winter and it lingers, regardless of daily weather fluctuations, before finally going away in the spring. (Though you can also experience SAD during the spring and summer months.)
In winter, what triggers SAD is not the overcast days, but the shorter days that result in the sun rising later than it would during spring or summer.
“You’ve got enough light on a cloudy day to treat winter depression, but it’s not at the right time,” said Dr. Lewy, who is an expert on internal clock disorders. For most people, the bright light therapy used for SAD should take place in the early morning hours, the closer to wake time the better, he added.
It might also be tempting to assume that melatonin, a hormone that helps induce sleep, could contribute to feelings of sluggishness on an overcast day, because it’s produced at night and is associated with darkness. But “melatonin is always turned off by the body clock in the morning, even in the absence of light,” Dr. Lewy said, so the hormone does not play a role in daytime fatigue.
If you find yourself dragging during the occasional cloudy day, it can help to focus on getting more rest at night and incorporating more energy-creating strategies into your day, such as taking movement breaks or focusing on what you eat. It might just be the boost you’re looking for.