Characters need a way to see in the dark. See Table: Light Sources for the radius that a light source illuminates and how long it lasts.

Characters with low-light vision can see objects twice as far away as the given radius.

Table: Light Sources
Object Light Duration
Candle 5 ft. 1 hr.
Lamp, common 15 ft. 6 hr. per pint
Lamp, bullseye 60 ft. cone* 6 hr. per pint
Lamp, hooded 30 ft. 6 hr. per pint
Sunrod 30 ft. 6 hr.
Torch 20 ft. 1 hr.
* A cone 60 feet long and 20 feet wide at the far end.