Why are babies so awake in the evenings?

Someone's got to do some research on this, because it is most peculiar. Emily's had a great day today - fed regularly, slept well (even allowed me to have a nap, marvellous) and is even now chilling on her playmat having had the day's penultimate feed. I'll try to feed her again at about 10pm and get both of us into bed straight after that.

The thing which needs research though is finding out why small babies are most awake between about 6pm and 11pm, give or take. Luckily we're able to get her into bed pretty much straight after her 10pm feed which is great - I remember being up with Isabel until midnight which is never my best time of day, and it was so draining. Even though Emily's awake, she's pretty peaceful most of the time, thank goodness - already displaying characteristics which are very different from those of her sister. Maybe she's just staying up to watch the Champions League with her Daddy - they both seem to be quite enjoying it, even though Husbandio looks rather nervous. Emily, luckily, can't yet see as far as the telly, so she's only getting the commentary. He'll make a footie fan of her yet - it's not worked with Isabel, so this is his last chance!