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.
Within a 24-hour cycle, the average sleep need for children is 9 hours, for adolescents (13-24 years old) is 9.25 hours, and for adults is 8 hours. As people move into senior ages, their sleep needs reflect those of adolescents. On average, most people need 1 hour of sleep for every 2 hours that they have been awake. 2  However, most people are not physically able to be awake for 2 hours, sleep for 1 hour, and repeat this cycle continuously.