My DS will only sleep for 45 mins at a time during the day and I am concered that this may affect his night time sleep. He used to sleep for 1.5 - 2 hours in the morning, then again in the afternoon with a short nap in the late afternoon (20 - 45 mins). Now, he is only going for 45 mins, 3 - 4 times a day. How can I get him to go back to the 1.5 - 2 hours??