Best Night Yet - But I Really Don't Know Why

When I woke up this morning I knew that I had the best night's sleep I've had in a long, long time. The problem is I don't think I did anything unusual yesterday - actually I went to bed earlier than normal - and this would usually cause me to sleep poorly. The only thing I did different yesterday was to listen to some meditation isochronic tones, as well as some insomnia ones, for about an hour - while doing something else (like writing or reading). I'll try to replicate the same behavior today and see if I get the same results tonight.