Prolonged useage can cause an irratation to sunlight, I know someone that uses if for SAD and swears by it. They stop in the spring when the sun comes out and well there is less of a need to use it.
Suposed to be good for depressive illnesses and general fatigue.
To make a tincture - from a book that I bought for £1 today.
1. put the herb in a large jar and pour on alcohol water mix. Should be about 25% alcohol and you can use vodka. Seal the jar and store for 2 weeks. Shaking occasionally.
2. Pour miture through a jelly bag into a clean jug. I asume that muslin will do the same thing or coffe filters.
3. Squeeze out the tincture from the bag. Ideally use a wine press and press the mixture into a clean jug. - I guess this is to get concentrated liquid aswell?
4. Pour the strained liquid into clean, dark bottles. Seal and store. Keep in a cool place and label.
20 drops 3 times a day of st johns tincture to treat fatigue.
You could
try this book