Hair on one side more than one side less, may be hair tie too tight, sleeping habits, seborrheic dermatitis and so on. 1. Hair tied too tight: usually like to tie a high ponytail crowd hair tied too tight, easy to pull the scalp leading to scalp follicle damage, so that the patient’s hair is reduced, part of the patient can appear on one side more and less. 2. Sleeping habits: some patients like to keep sleeping on the same side for a long time, which can easily lead to unilateral scalp pressure or friction for a long time, which can lead to damage to the scalp follicles on the pressurized side, making the hair on one side of the more and less. 3. Seborrheic dermatitis: the onset of this disease can make the patient sick scalp hair loss symptoms, such as seborrheic dermatitis occurs in the unilateral scalp can lead to damaged side of the scalp hair loss, making the patient hair more and less. When the hair on one side is more and less, the patient needs to clarify the cause as soon as possible, under the guidance of the doctor to carry out targeted treatment.