Hypothyroidism and fibromyalgia can hide SAD in plain sight

Having hypothyroidism or fibromyalgia alongside late-winter SAD makes everything harder — both recognizing it and treating it — because the symptoms overlap so much you can’t tell what’s driving what.

Fatigue, low mood, brain fog, weight changes, sleep trouble. These are hallmark symptoms of both SAD and hypothyroidism and fibromyalgia. So when a patient comes in feeling sluggish and down in February, is it their thyroid acting up? Is it a fibromyalgia flare? Is it the lack of sun? Probably all three, which means you might treat one and blame the other, or treat the wrong one first.

For recognition, the problem is that the seasonal pattern gets buried. A person with fibromyalgia might already feel terrible in winter from barometric pressure changes and pain. They won’t necessarily connect their worsening mood to the light cycle. Same with hypothyroidism — if their TSH is in range but they still feel awful, everyone assumes it’s “just the thyroid” when it might be SAD piling on.

Treatment-wise, you can