When someone stops using tobacco and nicotine products, it can take more than two weeks for the blood level of cotinine to drop to the level that a non-tobacco user would have and several weeks more for the urine level to decrease to a very low concentration.
Pre-school children require 10-13 hours a day. School-age children require 9-11 hours a day. Teenagers need about 8.5-9.5 hours on average. Most adults need 7 to 9 hours a night for the best amount of sleep, although some people may need as few as 6 hours or as many as 10 hours of sleep each day. Women in the first 3 months of pregnancy often need several more hours of sleep than usual.
For about a decade, the paediatric sleep community has recommended that children three to five years old need 11 to 13 hours, children five to 10 years old need 10 to 11 hours, and adolescents 10 to 17 years need eight-and-a-half to nine-and-a-half hours of sleep each night.