Setting your air conditioner to 26°C at night is generally considered optimal for balancing comfort, energy efficiency, and health. According to the Commonwealth Scientific and Industrial Research Organisation (CSIRO), maintaining a temperature of 26°C during the day and 22°C when sleeping is often recommended for energy efficiency.

However, individual comfort levels and health considerations may vary. Some studies suggest that temperatures slightly above or below 26°C can impact sleep quality. For instance, research indicates that room temperatures of 23°C and 30°C led to longer time to fall asleep, less deep sleep, and poorer sleep quality compared to 26°C.

Therefore, adjusting the temperature based on personal comfort, room size, humidity levels, and individual health conditions is advisable. Consulting with a healthcare professional or HVAC specialist can provide personalized recommendations.