Question: how much does it cost to leave your tv on?
Answer: It turns out that doesn't cost you too much, thanks to modern TVs: current EnergyStar models use only 30-60Watts for a 40" TV, so those 4 hours asleep cost you about 2 cents. If you have an old TV, however, it can consume as much as 400W - in that case your nap costs you about 15c.