After/before dark
Definition 1 of 2
Pro Tip 1/3Safety Concerns
Often implies potential danger or the need for caution during nighttime. 
Children shouldn't play outside after dark.
Pro Tip 2/3Cultural Events
Used when discussing plans that change after the sun sets, like festivals or gatherings. 
The lanterns look beautiful after dark.
Pro Tip 3/3Cinematic Suspense
In movies or books, sets a mood of mystery or suspense happening at night. 
The thief is planning to strike after dark.