Washing your hair daily can strip the scalp and follicles of the natural oil, or sebum, which can lead to dry, brittle hair, as well as a dry and irritated scalp. This can also cause your skin to overproduce sebum to compensate, which results in an oilier scalp and hair, thereby perpetuating a cycle of too much washing and excess oil production. If you find it hard to break the habit, try rinsing your hair with just water in between washes and letting it air-dry.