Sleep patterns of my 18 month old

Establishing good sleep habits is usually the most challenging part of a baby's day-to-day routine, I'm often told. This has never been a big challenge for me right from the start. The first eight weeks was tough on me and LG because he was a colic baby which made it difficult to sleep at night. Once the colicky phase was over, he was fast asleep anywhere between 8:30 p.m. and 9:00 p.m. every night. I can count the number of days he has been awake past 9:30 p.m. in the past year and half.

Night routine has never been a big problem. His number of naps during the day and the duration of each have varied over the months as he grew older. However, it has all changed over the past 4-5 weeks. Around the time he turned 18 months old, brought about a big change in his daytime naps. From two naps each spanning anywhere between 1 hour and 2 hours, it came down to just one nap. Earlier, he would wake up at 6:30 a.m. and then take a nap for an hour and half around 9:30 a.m. Afternoon nap for about the same duration would be around 2:30 p.m. This worked well for him and me as it gave me two breaks of roughly an hour and half each. He was full of energy when he got up too in time to go to the park in the evenings, comes back have dinner, play a bit and then go to bed.

Over the past few weeks, he has postponed his morning nap to around 11:30 a.m. /noon and wakes up at an odd hour of 1:00 p.m. for lunch and then stays awake through the afternoon only to get cranky by early evening. He understands that it is time to go to the park but his body is just not up to it. If I try to put him to sleep, he wakes up in twenty minutes getting further cranky which gets in the way of he getting a good dinner. I'm struggling hard in this phase trying to establish a long afternoon nap by postponing his morning nap by an hour or so; so that he has his lunch and sleeps comfortably.

Children this age need about 12-13 hours of sleep which he is anyway getting. The whole problem is with the timing. With the night sleep timing (9:00 p.m. - 7:00 p.m.) working fine, it's left to me to keep him engaged and get him into the rhythm of afternoon naps which most children his age are habituated to.

Related Reading:
Sleep patterns of my 17 month old toddler
Sleep patterns of a baby in the first 6 months
Changing sleep patterns of my baby - six months to 1 year
Establishing good sleep habits: 18 to 24 months