Our situation sounds similar to Kirst29 - we had to teach Caden at 12 weeks because we were exhausted carrying him around all day. Now after about 2 hours or so I notice yawning and rubbing eyes and grizzling. I give him a nice big cuddle, change his nappy and make sure he is comfy. I tell him he is going nigh nighs and stand cuddling him near his cot for about 30 seconds telling him it is beddy byes. I then put him in his cot, give him his teddy and he pretty much sticks his thumb in his mouth and closes his eyes. Within 15 minutes or so he falls asleep properly.

It is so much easier to do when he is not overtired, because then he grizzles alot more. Even with the insistent cries, I know he is only tired and can't switch off. It is not as if rocking him to sleep works because he prefers to be in his own bed, so I just tuck him and, say "goodnight Caden" and leave the room. If he grizzles intermittantly I let him go for 10 minutes or so and go in and re-tuck. If he is more upset, I go in, get him up and give him a cuddle then pop him back in and usually he falls asleep.

Make sure they are not teething, have restrictive clothing, wet nappy, etc. Even swaddle them or pop them in a sleeping bag if you need to.

Good luck