That's the finding of a researcher in Japan. He also discovered that surfing the web late at night can have an effect on your sleep habits. BREAKING NEWS!
OK, I'm being a little sarcastic here, but it seems like such an obvious conclusion that I'm sure you and I thought this was true even before any study was released.
(S18E19)
Homer: What are you, a travel agent? 'Cause you're sending me on a guilt trip.
I've been watching a lot of early Simpsons episodes lately, mostly from the first five seasons. I know many fans cite the earlier seasons as the best of the series, but I tend to disagree with the notion that the show was only good up to a point and all subsequent seasons are a complete waste. It's easy to say "everything after season six is crap," but you're disregarding A LOT of episodes when you make a statement like that. I try to judge each episode on its own merit, regardless of the season.
It's certainly not wrong to prefer some seasons to others, as humor is always subjective, and, in the case of The Simpsons, I think there are numerous variables that come into play as to why some still love it and some abhor it. I won't go into that here, though.