Can babies sleep too much?

The past couple of days, Milo's been sleeping a lot.

Tue night he went down for the night at 10pm, slept til 5am, had a feed and was asleep again by 5:30. Slept til 9am, tried feeding him but he wasn't hugry and was falling asleep. He then slept til noon, had a bit of a feed, and slept again til 3pm. Was awake for a couple of hours in the evening and slept 10:30 - 6:30am that night.

I reckon in 24 hours he would normally have between 10 - 12 hours sleep, but the past few days its been more like 16 - 18.

I didn't seem hungry, just wanting to sleep, and when I did offer him the breast he'd refuse, or fall asleep in my arms.