For the most part the pools and hot tubs are open 24/7. The only time the close is for cleaning and treating with chems.
Remember that the pools are close to the rooms so use good sense and try not to be too loud and wake up the sleeping guests! LOL
There are pool hours posted that indicate the pools to be closed during the evening, but the hours aren't enforced, and guests do occasionally use the pools at night. You don't mention which resort you'll be visiting, but there are more private pools that would better for evening use at each resort.
CN - the main pool is near the restaurants, but there is a smaller pool and hot tub near the water sports hut that is perfect for an evening dip.
CSA - both the original pool and the pool with the swim-up bar are near restaurants, but there is a large pool and hot tub across the street at the sports facility
CTI - the new pool with the swim-up bar is not near restaurants and is more private.
CSS - to the best of my recollection, any of the three pools at this resort would be fine for a nighttime swim
I know everything, and I'm always right (just ask my husband).