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.
Fatigue is also common when you're feeling down. How much sleep do you need? The need for sleep can vary quite a lot between individuals, although it's usual to require less sleep as you get older. Children. Small children often need a lot of sleep. Toddlers, for example, need between 14 and 16 hours a day. The need for sleep slowly declines through childhood. Most schoolchildren will need at least 10 to 12 hours of sleep to be at their best during the day. Teenagers function best on 9 hours per night, but few get that much.