Our hair can grow by about 1.5 cms every month, but it is normal to loose about 100 hairs a day.
Hair growth happens in cycles. There are 3 cycles: anagen, catagen, and telogen.
Anagen is when the hair grows, i.e. the growth stage. This is the longest stage and about 90% of your hair will be in this state which lasts up to 6 years.
Catagen is the second stage and is also the transition stage. During this period, which lasts up to 3 weeks, the hair follicle will shrink.
This is then followed by the final stage, the Telogen stage, that is the resting stage. This is when hair starts to fall out as the new hair follicle pushes out the old one and moves back into the Anagen stage. The Telogen stage takes about 3 months.
When you experience an extreme stress (like a bereavement, work change, divorce or illness) your body can push your hair into the Telogen stage prematurely. This then results in noticeable hair loss. This condition is called Telogen Effluvium.
Also see my blog below about thyroid and hair loss.