Baby Sleep

My LO is 5.5 months old and he sleeps great at night I rock him to sleep then lay him in his pack n play and he sleeps all night till about 4 in the morning he getting restless then I put him in bed with me and he'll sleep till 6:30.. but during the day when he naps I literally can't put him down cause he'll wake up. Any suggestions on how to keep him asleep for naps?