If you’re like most people (and by most, I mean 99% of U.S. adults), you love the spring and summer, not least because of the long hours of daylight that will get longer still this weekend, when clocks are turned one hour forward. But if you’re like me (and the rest of the 1%), you have a decidedly different take on things. That’s because we are part of the small minority of people who suffer from what is known as summer—or reverse—seasonal affective disorder (SAD). We all know about winter SAD, which affects about 5% of the U.S. population and leads to low-grade—and sometimes high-grade—depression as sundown comes earlier and daylight hours shorten. There are plenty of suspected causes for winter SAD, including a reduction in the neurotransmitter serotonin in response to lower light levels and an anomaly in a gene that governs melanopsin, a receptor in the retina that influences circadian rhythms, hormone secretions, and cognitive processes. When it comes to summer SAD—which leads to low moods as days get longer—the research is less robust, but investigators are beginning to look at a handful of possible triggers. Some examples: Too much light can spur overproduction of melatonin—a hormone that governs sleep—leading to disruptions in the sleep-wake cycle and resulting in depression. Seasonal pollen may play a role, causing an inflammatory response in vulnerable people that affects the production of norepinephrine, a neurotransmitter that influences mood. Heat and humidity may also affect levels of norepinephrine, as well as serotonin and dopamine. Whatever the causes, when you set your clocks forward on Saturday night, spare a thought for the small group of us who will make the change not with joy at the arrival of the light, but sorrow at the loss of the dark. Spare us the sunny summer. We’ll take a cloudy sky, a chilly drizzle, and a 4:30 PM sundown anytime. |
