Hello Darkness, My Old Friend

Why your brain is so SAD

Dana G Smith
Elemental
Published in
4 min readDec 8, 2020

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Image: Fertnig/Getty

This is a modified excerpt from Inside Your Head 🧠, a weekly newsletter exploring why your brain makes you think, feel, and act the way you do, written by me, Elemental’s senior writer and a former brain scientist. Subscribe here so you won’t miss the next one.

I’ve been feeling a little sad lately. I’ve never been a winter person, but this year, with no holiday parties or vacations to lighten the mood, the short, cold, gray days feel particularly bleak. Not to mention the layer of grief and fear that comes from the tenth month of a pandemic that’s killing more than 2,000 Americans every day. (Aren’t you glad you decided to read this uplifting article?!)

I also know, however, that this feeling isn’t really me — or at least it’s not my normal state of being for nine months out of the year. It’s seasonal affective disorder (SAD!), with some pandemic fatigue and despair sprinkled on top.

Seasonal affective disorder afflicts 5% of U.S. adults, although numbers vary depending on geography. For example, nearly 10% of people in Alaska experience SAD, whereas the prevalence in Florida is only 1.4%.

SAD is more than just the winter blues, writes Ashley Laderer in an Elemental article on seasonal affective disorder from last winter. “It’s typically a repetitive mood cycle where each year, as fall and winter come along, the person starts to experience depressive symptoms — low mood, anhedonia [inability to feel pleasure], poor concentration, sense of guilt or worthlessness, changes in appetite and weight, and changes in sleep,” says Paraskevi Noulas, PsyD, a clinical assistant professor in the department of psychiatry at NYU Langone Health.

Scientists think that seasonal depression is linked to changes in your circadian rhythm — the 24-hour internal clock that dictates many of your hormone levels and, as a result, your energy levels throughout the day. Morning light triggers the start of the cycle each day by activating light-sensitive cells in the suprachiasmatic nucleus (SCN) — a group of about 10,000 neurons in the brain that act as the body’s pacemaker. In the winter, weaker sunlight, less time outside, and shorter days can deprive the SCN of those important light cues, throwing off the body’s schedule.

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Dana G Smith
Elemental

Health and science writer • PhD in 🧠 • Words in Scientific American, STAT, The Atlantic, The Guardian • Award-winning Covid-19 coverage for Elemental