So, I too, was wondering if sleep was included, but I looked into it and this is what I found.
"You use energy no matter what you're doing, even when sleeping. The BMR Calculator will calculate your Basal Metabolic Rate (BMR); the number of calories you'd burn if you stayed in bed all day.
The Harris Benedict Equation is a formula that uses your BMR and then applies an activity factor to determine your total daily energy expenditure (calories). The only factor omitted by the Harris Benedict Equation is lean body mass. Remember, leaner bodies need more calories than less leaner ones. Therefore, this equation will be very accurate in all but the very muscular (will under-estimate calorie needs) and the very fat (will over-estimate calorie needs)."
So what I take from this, is that your BMR includes sleep, then you factor in the Harris Benedict Equation for you activities. I think sleep may be included in activities for naps or something. I'm no expert, but this is how I understood it. I would love to get a definite answer on this though.