Researchers at the Johannes Gutenberg University Mainz (2021) found that night-time environmental noise increases cortisol levels, which can raise blood pressure and strain the heart. In a camper with thin walls, an open window amplifies noise, causing subconscious tension. Additionally, an open window promotes condensation and reduces security.
Recommendations include airing out the camper before sleep, using a roof vent with mosquito net or a ventilation valve, brief airing, and a quiet fan.