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.
While sleep requirements vary slightly from person to person, most healthy adults need between 7 to 9 hours of sleep per night to function at their best. Children and teens need even more. And despite the notion that our sleep needs decrease with age, most older people still need at least 7 hours of sleep. Since older adults often have trouble sleeping this long at night, daytime naps can help fill in the gap.