How long before a nap should a subject stop smoking?

The correct answer is based on the understanding of how nicotine affects sleep patterns and the processes involved in preparing for a nap. Nicotine is a stimulant that can interfere with the body's ability to fall asleep by increasing heart rate and promoting alertness. Stopping smoking about 30 minutes before a nap allows enough time for some of the nicotine's stimulating effects to wear off, making it easier for a subject to transition into a restful state.

This time frame is generally recommended to minimize the likelihood of experiencing heightened alertness or difficulty falling asleep due to nicotine. Additionally, it aligns with the general guidelines for managing stimulant intake when it comes to sleep hygiene practices.