An abnormal amount of follicles in the resting stage results in noticeable hair loss. A normal amount of hair loss is only 50-100 hairs, according to Dr. Ken Washenik from the North American Hair Research. "Approximately one out of every 10 scalp hairs is normally in telogen," he said. Finding clumps of hair on your pillow, on your clothes and in the drain is a sign that something is not right. Everyone has a few strands fall out throughout the day, but it is mass quantities that are cause for concern. 

"If the number of hair follicles producing hair drops significantly for any reason during the resting, or telogen phase, there will be a significant increase in dormant, telogen stage hair follicles. The result is shedding, or TE hair loss," according to the American Hair Loss Association. 

Though there is little research on telogen effluvium, and treatments are limited, it is the second most common cause of hair loss. The reason for the thinning hair is simply too many follicles in the resting phase at the same time, but the damage is not permanent, and it does grow back once the phase passes. "Normal shampooing can continue because this only loosens hairs that were going to come out anyway," according to Dr, Gary Cole. These follicles have white bulbs on the ends.