The amount of sleep each person needs depends on many factors, including age. Infants generally require about 16 hours a day, while teenagers need about 9 hours on average. For most adults, seven to eight hours a night appears to be the best amount of sleep, although some people may need as few as five hours or as many as 10 hours of sleep each day to feel fully refreshed. Women in the first three months of pregnancy often need several more hours of sleep than usual. The amount of sleep a person needs also increases if he or she has been deprived of sleep in previous days. Getting too little sleep creates a sleep debt, which is much like being overdrawn at a bank. Eventually, your body will demand that the debt be repaid. Our bodies do not seem to adapt to getting less sleep than we need. Unfortunately, while we may get used to a sleep-deprived schedule day after day, our judgment, reaction time, and other functions are still impaired.