This week my 16 week old has been more tired than usual.
He can only stay awake for an hour in the morning after feed, bath and changing. Then during the day his awake time is less than usual. I'm not sure what's going on!
That sounds like he's hitting a growth spurt! Babies normally have one around four months, mine was a cranky madam for about a week or so at that time. If you're worried then maybe give your health visitor a call.