Configure the airflow velocity of your air conditioner to a comfortable sleeping environment, as a study reveals when airflow is directed at a human body at an insensible velocity, it may increase your heart rate and affect sleeping positions.

The results, in the journal of Energy and Buildings, indicated that the participants have significantly greater body movements, an increased heart rate and a higher frequency of walking in the room that has the AC with a mean velocity of 0.14 m/s.

It implies that the cold airflow may have a greater impact on the overall sleep of the participants with lower physical strength or a greater sensitivity to cold.

According to researchers at the Toyohashi University of Technology in Japan, airflow from an AC stimulates the human body while sleeping and impacts on sleep conditions even if the mean airflow velocity is lower than an insensible level.

It suggests some AC setting may have an unintentional negative impact on sleep quality despite the comfort the person feels.

The research team, led by Professor Kazuyo Tsuzuki, had the subjects sleep in two bedrooms using ACs set at different airflow velocities.

Then they made a comparison of the depth of sleep and body temperature control using electroencephalogram (EEG) measurements as well as subjective reporting by the subjects.

In this study, a comparison was made on the influence of two types of airflow, mean velocity of 0.14 m/s (general AC) and 0.04 m/s (customised AC), both at a room temperature of 26 degrees C.

The participants felt cooler with the higher airflow velocity during wakefulness and sleep.

However, no significant difference was observed in the feeling of comfort, length of sleep depth, skin temperature, rectal temperature or sense of warmth or coolness in each subject before sleeping.

The result is the useful clue as to how to configure the airflow velocity of an AC to create a comfortable sleeping environment.