Currently, there is no widely accepted or standard method for assessing the number of hairs shed daily. The belief that shedding 100 hairs a day has not been scientifically validated and does not indicate whether shedding is constant or if it varies by age or sex.
But a standardized 60-second hair count is a reliable method for assessing hair shedding, says Dr. Carina Wasko, a researcher at the Baylor College of Medicine in Houston. She studied hair loss in sixty healthy men (half age 20 to 40 and half age 41 to 60) without evidence of baldness.
Participants were given identical combs and instructions to wash hair with the same brand of shampoo for three consecutive mornings. On the fourth day, they were asked to comb hair forward for 60 seconds over a towel before shampooing. The men combed their hair and then counted hairs shed for three consecutive days. This procedure was repeated six months later.
Participants age 20 through 40 shed an average of 10.2 hairs per 60-second test. Men age 41 to 60 shed an average loss of 10.3 hairs per 60-second test. The hair counts were repeated and verified by a trained researcher, making the 60-second hair count is a simple, practical and objective tool for monitoring conditions associated with shedding.