I can vouch for this too, but the down side for me is that because I've done this for so long, it's nearly impossible for me to fall asleep quickly if the room is remotely warm already...
When I was younger, and living in an unconditioned house in central Florida, I used to sleep with a big box fan at the foot of the bed pointing directly at my feet. It kept me cool and kept the mosquitos at bay as well
Probably less than you think. Heat loss or intrusion from the environment is linear in the difference between the environmental temperature and the interior temperature. Since it is cooler at night, it will generally be less expensive to turn down the temperature at night. Even in Florida, the average low in August is 72F. There's not much of a difference between this and 68F, so your AC will not have to work very hard to keep the house cool in the evening.
If you're concerned about energy usage, it's by far more important to tolerate higher temps during the day than during the night. Conversely, in the winter, you can afford to warm your house up a little more during the day, but if you want to sip energy, you need to set the lowest acceptable temperature at night.
You can optimize this further by putting a minisplit or a window unit in your bedroom. If your bedroom is small compared to your dwelling, you can save some serious energy this way. Generally speaking, the cost of climate control will scale in the surface area of the climate controlled volume, and obviously a single bedroom has much lower surface area with the environment than the whole house. This is also why it takes so much less energy to control the climate of a given apartment unit than a house of the same square footage.
