Improving air circulation is key to maintaining a comfortable sleep environment. Open windows or use trickle vents to allow fresh air to enter the room. Consider using a dehumidifier to manage humidity levels, keeping them below 60%. The practice of 'Lüften,' or airing out rooms for 10-15 minutes daily, can help purge stale air and moisture. For persistently hot rooms, investing in air conditioning or fixing ventilation systems may be necessary.