The answer to this question is a bit complicated and depends on several factors. In general, it is not recommended to leave your attic fan on all night. Here are some things to consider:
1. The purpose of an attic fan is to remove hot air from your attic. If your attic is not well-insulated, the fan will also remove cooled air from your home, which can make your living space uncomfortable.
2. Attic fans are typically noisy, so leaving it on all night may disturb your sleep.
3. If you have an electrical system that is not up to code, leaving the fan on all night could be a fire hazard.
4. Some experts believe that leaving an attic fan running continuously can shorten its lifespan.