Interestingly, however, hairs do not grow at the same rate throughout the day; there are times during the day when they do and times when they do not.
Hair begins to grow in the morning, usually between 10:00 and 11:00 a.m. The hair grows fastest at that time, followed by the rest of the day. After that, the speed of hair growth gradually slows down, but it starts to speed up again between 4:00 and 6:00 p.m., and then it slows down again at night. Then it slows down again, and at night it hardly grows at all.
Unfortunately, it is still not well understood why they grow in this way.