@leon-damjanov, it sounds like you run on stress hormones to compensate for poor thyroid function. Adrenaline raises temps and lowers TSH, giving the false impression that thyroid function is good. The biggest give away to me are cold extremities. Adrenaline cuts off circulation to extremities to keep vital organs warm when thyroid function is poor. The stress of darkness and fasting at night may be triggering adrenaline, causing your temp to be normal in the morning, while eating throughout the day lowers adrenaline, resulting in lower temps and revealing what your actual thyroid function is. Regarding weight, I’m thin, consume a lot of calories for my size and activity level, and have a history of running on adrenaline due to a weak thyroid. Ray Peat talked about people like us whose hypothyroidism often goes untreated because we aren’t overweight.