Sound does travel faster when temperatures are warmer, so technically, it is faster when the sun is up. However, that does not mean it is necessarily more audible.
Warm air provides less resistance for sound waves, allowing them to travel faster with the same amount of force. However, warm air also causes them to refract upward. Cooler air causes sound waves to refract downward toward the Earth, and generally, there is less ambient noise to compete with during common sleeping hours, leading to the common misconception that sound travels faster at night (because it's easier to hear). Light is not a factor in how far sound travels, only temperature.