A lamp left on can make an ordinary return feel expected.

Coming back to a dark house is a small daily message that nothing was waiting. A light burning in a window says the opposite without anyone having to be awake for it: your return was accounted for. The gesture takes no effort and is almost entirely symbolic, which is exactly why it works.

Leave a light on for whoever comes in after you this week, or for yourself before you go out for the evening. If you live alone, a timer does the same job. Notice the difference between arriving into darkness and arriving into a lit room.