posted by kelsey .
When people sleep, their metabolic rate is about 2.6 10-4 C/(s·kg). How many Calories does a 69 kg person metabolize while sleeping 9.0 hours?
Multiply that metabolic rate by the mass (69 kg) and the number of seconds in 9 hours. The answer will be in Calories. These are Kilogram Calories, sometimes called "food" calories.