Air Conditioning at Night: How to Set It and the Potential Health Risks

“Air conditioning is part of the broader concept of homeostasis in the human body,” explains the specialist. “Homeostasis refers to the body’s ability to maintain stable internal parameters, including body temperature.

During the night, body temperature tends to decrease slightly, which is why it is important to gradually reduce the intensity of cooling as well.”

While we sleep, we are less aware of changes in room temperature and cannot promptly adjust the air conditioner. If the room becomes too cold, the body experiences a “thermal shock” and is forced to work even while we are resting, activating mechanisms such as shivering or vasoconstriction to prevent heat loss. At a biological level, this can fragment sleep and prevent truly restorative rest.

“Sleeping in a well-conditioned environment allows for more restful sleep, which is extremely valuable for a person’s well-being,” adds Dr. Cappelletti. “If the temperature is too cold, however, you may wake up feeling more tired.”

“Air conditioning is not harmful in itself. On the contrary, it offers significant benefits, including temperature control, dehumidification and air filtration,” says the specialist. “However, incorrect use or poor maintenance can make it potentially harmful.”

Respiratory Problems

Air conditioning reduces indoor humidity. When the air becomes excessively dry, it can irritate the mucous membranes of the respiratory tract, affecting the mucus layer that helps protect the airways. The most common problems include:

• inflammation of the upper respiratory tract, including pharyngitis, laryngitis, rhinitis and dry cough;
• flare-ups of chronic respiratory conditions in people who already have asthma or COPD (Chronic Obstructive Pulmonary Disease);
• infections or other problems associated with inadequate maintenance of air-conditioning systems.

“Air filtration is one of the major benefits of air conditioning, but it can be a double-edged sword: if filters are not cleaned regularly, dust, mold and other microorganisms can accumulate. In systems that are not properly maintained, there may also be an increased risk of bacteria such as Legionella proliferating, particularly under specific system conditions,” explains the specialist.

Cold air can also temporarily slow the movement of the cilia lining the respiratory tract, reducing the efficiency of the body’s natural defense mechanism that helps remove particles and microorganisms from the airways.

Systemic and Muscular Problems

In addition to affecting the respiratory system, cold air and direct airflow can have an impact on the muscles and cardiovascular system. The main effects include:

• muscle contractures and localized inflammation, such as the classic stiff neck, lower back pain and joint pain, particularly in older adults;
• changes in blood pressure associated with cold-induced vasoconstriction.

These conditions may place greater stress on people with high blood pressure or heart failure, who may have a reduced ability to adapt to sudden changes in temperature.

The risks associated with incorrect use of air conditioning at night may be greater for more vulnerable individuals, including:

• older adults, who have less effective thermoregulation and a reduced ability to perceive heat and thirst;
• children, whose thermoregulatory systems are still developing and who tend to uncover themselves easily during the night;
• pregnant women and people with respiratory, heart or kidney conditions, for whom maintaining thermal balance may help prevent symptoms from worsening.

To keep your home cool without compromising health and well-being, it is important to follow a few practical recommendations:

• set the temperature so that there is a difference of approximately 4-5°C compared with the outdoor temperature, avoiding excessive temperature changes;
• consider using dehumidification mode, which is often enough to reduce the sensation of heat without excessively lowering the bedroom temperature;
• activate the “Night” or “Sleep” mode, which automatically and progressively reduces the intensity of the airflow during sleeping hours;
• never direct the airflow straight at the person or the bed; instead, adjust the vents so that cool air is distributed evenly throughout the room;
• regularly ventilate indoor spaces during the day and ensure proper periodic maintenance of the air-conditioning system.

“Especially for older adults, simply dehumidifying the room may be sufficient in many situations,” the specialist emphasizes. “It is also important to ensure adequate air exchange during the day and keep the system in good hygienic condition.”

If respiratory or muscular symptoms persist even after correcting how the air conditioner is used, it is advisable to consult a doctor for a specialist assessment to rule out other possible causes and determine the most appropriate treatment.