There have been a number of studies that show it’s important to keep cool when you sleep. The evolutionary logic here is pretty. If you slept outside at night, as humans did for millions of years, you would notice the temperature naturally drops during the nighttime hours.
There are many new products that can help recreate this, like cooling beds, etc. The easiest approach is simply to lower the thermostat at night a few degrees. Most people have programmable thermostats, and so this can be set very easily.