It's always ~7:30 PM.
Gravity and air are normal, and clouds and winds and storms exist, but there's no moon, and the sun is always just touching the horizon, without ever moving in the sky. The weather doesn't vary much. Temperatures never stray from 65°–75° Fahrenheit.
(Assume that the exact circumstances that cause this state are irrelevant. It might just be magic.)
The civilization in question has achieved roughly iron-age technology. They're peaceful and agrarian. They have a rudimentary writing system. They have abundant freshwater from lakes and streams. They have some neighbors they can trade with.
- How would people measure time, either on a day-to-day scale or year-to-year scale?
- What would their sleep cycles look like?