I am always afraid I am going to be late to the airport, and miss a flight. When I get in after a long day of travel, late at night, the only thing I want to do is go to sleep. About 20 years ago, we had an early morning flight from Gatwick and Jay made reservations for a hotel attached to the terminal for the night before. It was so much less stressful than staying in the city and trying to get to the airport for a 8 AM check in for a 10 AM flight. I started doing the same.
The hotel above is not much to look at from the outside, but it is 3 minutes from the terminal at Heathrow. On the trip we stayed there, we took a daytime flight from DC to London, leaving at 9 AM and arriving at 9 PM (21:00.) I booked this hotel for the first night and then we went on into London the next morning. On the way back, we stayed at the same hotel the night before our flight home. (A Holiday Inn.)