Researchers at the University of Pennsylvania claim that watching TV before bed leads to poor sleep. One of their suggested reasons is that the telly is replacing the vigorous exercise that might tire us out.
Leaving aside the bizarre idea that people would be exercising late at night if they weren't monitoring Big Brother, the theory has another big hole in it. A couple of days ago, researchers at the Walter Reed Army Medical Centre in Washington DC reported that exercise doesn't, in fact, tire us out. It actually keeps us awake.
I would put the two groups of boffins in touch with each other, but I'm feeling a little sleepy at the moment. Another day.