Lack Of Sleep

This does play a role in altering the hormone balance in one's body such that it leads to hair loss as it interferes with the regular hair growing cycle. In men, hair loss is attributed to the conversion of testosterone to DHT in the body. Since the lack of sleep is a result of our fast-paced and modern life, there is every reason to suggest that stress and fatigue will result in hair damage of both men and women.

Source: http://www.hairparlor.com