Greying begins to get apparent after the increased shedding of the thicker, darker hairs coupled with an enhanced growth of thinner white hairs. Explains dermatologist and cosmetologist, Dr Sadhana Deshmukh, "This shedding of hair can take upto a few months, but there are some cases of 'overnight greying' that happen due to a sudden fallout." Greying also has a pattern. In men, greying starts at the beard, then moustache, side locks and spreads to other parts of the head over time. Chest hair turns grey only a few years later. For women, grey hair starts from the temples, then it spreads to the sides.