Lighten your hair with lemon juice.
Sun exposure will lighten your hair, although very slowly. The acid in lemon juice can help it happen faster. It won't turn dark hair blonde, but it will lighten your hair slightly.
Put some lemon juice on your hair where you want it lighter and go out in the sun. If you have dark brown hair, it probably won't turn blonde but will give you red/auburn highlights. It seems to work best on people who have dirty blonde or light brown hair.
Use it on dirty hair, rather than freshly washed hair. That way the oils in your hair will protect it from the drying effects of lemon juice.
Squeeze the juice out of a few lemons, mix it with a third amount of water and put it in one of those cheap plastic spray bottles. Spray it all over your hair before going outside for all over lightening.
Sorce: www.hairstyle.com/hair-articles/home-hair-care-tips.htm