The energy saved by sleeping eight hours is approximately what?

• A. the same as energy from eating a piece of toast
• B. twice the energy from eating a piece of toast
• C. half as much energy as energy from eating a piece of toast
• D. much more energy than a piece of toast

Answer: (A)

The idea being tested is how much energy the body uses while sleeping and how that compares to the energy you get from food. Even when you’re asleep, your body still burns calories to keep vital functions going, but at a lower rate than when you’re awake. Over eight hours, the amount of energy used is roughly similar to the energy you’d get from a small snack. A typical slice of toast provides about seventy to a hundred kilocalories, which is a convenient, everyday reference point for estimating this. So the energy saved by eight hours of sleep is approximately the same as the energy from eating a piece of toast. Of course, individual differences in metabolism mean the exact amount can vary, but the general idea is that a night’s sleep saves a snack’s worth of energy rather than a much larger amount.