Hard To Get Them Nap

Lately, I've been having a hard time getting Alycia and Sherilyn to nap in the afternoon. They used to take their afternoon nap at 2:30pm, latest by 3pm but now, they don't even appear worn out or sleepy at 4pm or 5pm. I thought they no longer require their daytime naps but I was wrong coz by 6pm, they would go super cranky if they don't get their dose of daytime nap. Now, I have to resort to holding a cane to threaten them to take their nap each day. I hate to do this but that's the only way to get them to sleep. Last night, the same thing happened. I was so frazzled and sleepy at around 11ish pm but the gals' batteries seem to be still full to the brim. So again I brought out the cane and they quickly ran back to bed and dozed off after much fuss. I fell asleep clutching to the cane and woke up at 12:30am to ease myself, then crept downstairs to do some work on the computer and went back to bed an hour later. It's really tough being a WFHM.