Adding another data point. Live in Ireland. Sun doesn't provide any benefit in the winter as the sun's rays get blocked by atmo. I consume no food with suppleme

Adding another data point. Live in Ireland. Sun doesn't provide any benefit in the winter as the sun's rays get blocked by atmo. I consume no food with supplements. I'm 100kg/220lb moderately athletic, nearly 50 y/o. 1000IU is not enough to keep the SAD (Seasonal affective disorder) away. Its like my batteries are running low. I consume 2000IU daily. If I miss two days in a week, I can feel the difference. With covid-19, I've had no colds or flu so can rule out the occasional virus for same effect. Self treating for 12+ years. Try to consume the minimum to feel "awake"