First off here is how you can determine about how many calories on average you’re burning. During sleep, a person's weight and the number of hours he/she sleeps determine how many calories are burned.
Normally, a person burns about 0.42 calories for every pound in one hour of sleep. For instance, a 150 lb. person burns about 63 calories in one hour. If this person sleeps for eight hours total, he/she burns 504 calories for the whole duration. Just multiply the average rate with every pound of weight and number of hours of sleep. Therefore, the heavier a person is, as well as the longer a person sleeps, the more calories are burned.
Or you can just go to this link and the FitWatch calculator can do the math for ya J
Here are some of the factors that contribute to the amount of calories burned during sleep:
Muscle mass impacts the rate of burning calories. Even while sleeping, a person with greater muscle mass burns more fats and sugar, compared to a person with average muscle mass, or worse, a person with more fats. A single pound of muscle consumes 50 calories for one whole day, while a pound of fat consumes only nine calories.
Metabolism also plays a key role in calorie burning. An active person requires more energy and burns more calories. On the other hand, a person with slower metabolism rate consumes less energy. It is during sleep that a person replenishes what he/she has lost during the day. Because an inactive person does not spend much energy during the day, there is not much energy to replenish when he/she sleeps.
You'll burn more calories --- several extra hundred each night --- while you sleep if you keep your body temperature cooler. When you bundle up in heavy blankets and wear thick pajamas, your body does not have to work to supply natural body heat. Sleeping with a cooler body temperature, sans excess blankets and cozy pajamas, makes your body's thermostat work to provide natural body heat.
LACK OF SLEEP
Substituting exercise for sleep time sounds like it would be an ideal way to lose weight, but it's actually not. Not getting at least seven hours of sleep each night can contribute to extra fat storage. When your body gets fewer than seven hours of sleep, hormones that increase your appetite kick into high gear. This will likely make you eat more than you would if well-rested. In addition to being hungry, your body will also crave carbohydrates and other high-calorie foods.