Science News

Article originally written by Annabella Yu ’26.

Holidays are coming up: Diwali, Thanksgiving, Christmas, and Kwanza. But why does it feel like we can’t enjoy these days to the fullest? Every day leading up to these celebrations are spent trying to catch up with the mountains of work and commitments, doing the best we can to sluggishly make our way to the end of the day, then endlessly scrolling through social media until our eyes become tired and our head spins. Finally, we end the day with no assignments finished, an exponentially growing to-do list, and waking in the morning to worry–unable to face our problems.

Could this be the effect that school has on kids today? Possibly. However, science and medicine suggest another reason for the tired episodes that happen mostly during the fall and winter seasons.

Seasonal affective disorder, or SAD (a very fitting acronym), describes the condition of a type of depression triggered by the change in seasons. (Some people are also affected by a rare branch of SAD: “summer depression” starting in late spring and early summer; ending in the fall.) Common symptoms of SAD are feelings of sadness or hopelessness, lack of energy, loss of interest in usual enjoyable activities, oversleeping, and weight gain. 

To put it simply, because of the shorter, colder days with less visible sunlight, the circadian rhythm (body’s internal clock) is disrupted. The circadian rhythm influences sleep cycles and hormone release, both of which are closely related to mental health. 

When exposed to less sunlight, the signal for certain neurotransmitters, such as serotonin and melatonin (both playing a role in mood regulation/sleep-wake cycles respectively), will drop or rise significantly. For instance, a drop in serotonin can lead to difficulties in emotional processing, pain processing, and other important neuroprocesses. In contrast, lack of sunlight increases the production of melatonin, a hormone that causes drowsiness. Because melatonin responds to darkness, too much melatonin can lead to one feeling tired and irritable. 

Other effects of chemical changes caused by changes in seasons include: purposeless physical activity (inability to sit still, pacing, etc.), feeling worthless or guilty for no apparent reason, difficulty concentrating/feeling motivated, reduced social contact, and thoughts of death or suicide. Depending on the type of SAD, there can be differences in how a person is affected. One with summer depression may have trouble falling asleep (insomnia), feeling agitated and anxious, while people with winter depression may oversleep and constantly feel tired.

Anyone can have SAD, but certain factors that may contribute to the development of SAD include a person’s gender, genetic predisposition, geographic location, and age. Approximately 5 percent of adults in the U.S. experience SAD, and it lasts about 40 percent of the year. It is more common among women than men (likely due to hormonal fluctuations). A history of depression can also put one at higher risk of developing SAD. How close one is to the equator also seems to be a factor, as that determines how much sunlight a person receives. Stress is also a big contributing factor, as pre-existing stress can add onto the developing symptoms that affect sleep and mood by themselves already. 

There are treatments for SAD, such as light therapy or cognitive behavior therapy (talk therapy). It is important to talk with a professional if you think you may be affected (or have friends/family) who may have symptoms of seasonal depression.

Happy holidays! 

Sources:

Seasonal affective disorder (SAD): Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651

How to fight seasonal depression: Columbia
https://www.cuimc.columbia.edu/news/how-fight-seasonal-depression

Seasonal affective disorder: American Psychiatric association
https://www.psychiatry.org/patients-families/seasonal-affective-disorder

Seasonal affective disorder: It’s more than just “feeling blue”: McLean Hospitals
https://www.mcleanhospital.org/essential/seasonal-affective-disorder-its-more-just-feeling-blue