I'm commenting to express interest in that citation, and will go looking for it myself if you don't find it. If I had to bullshit a mechanism, I would say that

I'm commenting to express interest in that citation, and will go looking for it myself if you don't find it. If I had to bullshit a mechanism, I would say that, for well fed mice, activity increases with the amount of time since the last meal, so mice on the early dinner diet would be more active in the mornings before breakfast. To test this, I would see if I could get the effect to go away by feeding mice as soon as they woke up, and then 10 or 14 hours later.