I'm taking 900 mg a day of st. John's wort for depression (300 mg x3) it's working wonders for my mood but makes me very tired. Is this normal? Thanks

St. John's Wort. Yes, fatigue/sedation is one of the more common potential side effects of st. John's wort. Gi symptoms, restlessness, skin reactions, photosensitivity, sexual dysfunction (including impotence), dizziness, and dry mouth are others.
It's possible, but.. It is good to hear that the st johns wort is helping the depression. It also means that it is likely to be on the mild end of the depression scale. The tiredness: not sure that it is a side effect of the wort. Perhaps it is part of an abnormal sleep pattern or a symptom of the depression. If it persists more than three weeks, it's worth discussing the whole issue with your primary care physician.