The Vascular Game in the Interplay of Cold and Heat
During the hot summer days, most people rely on air conditioning to cool down, but frequently moving between environments with large temperature differences can easily trigger severe contraction and expansion of blood vessels, leading to headaches.
The brain's blood vessels are extremely sensitive to temperature changes. When a person is exposed to 40°C heat for half an hour and suddenly enters a 20°C air-conditioned room, the blood vessels will quickly constrict, resulting in relative insufficiency of blood supply to the brain; when going outside again, the blood vessels rapidly expand, causing a circulatory imbalance. This "vascular game" brought about by alternating cold and heat is the mechanism behind "cold-heat type headaches."
Ms. Lin, a counselor at a university (32 years old), frequently moved between her air-conditioned office and outdoor patrol points during exam week. Every evening, she began to feel a throbbing pain in her temples, accompanied by slight nausea and dizziness. She thought it was a migraine caused by stress, but after a neurological examination, she discovered it was a vascular headache caused by frequent temperature changes.
If this kind of cold and heat stimulation is ignored for a long time, it can exacerbate the existing migraine condition, increasing the frequency of attacks and even leading to a malignant headache syndrome.
Dehydration: The Most Underestimated "Invisible Enemy"
Many people think that drinking cold beverages in summer is equivalent to rehydrating, but in reality, the body's true need for water is far greater. Dehydration is one of the most easily overlooked headache triggers, especially prevalent in hot weather.
Headaches caused by dehydration are closely related to reduced blood volume. When the body is lacking water, blood viscosity increases, leading to decreased perfusion of the brain's microvessels, which in turn triggers persistent dull pain. This type of headache is often located in the forehead or throughout the head, commonly accompanied by dry mouth and fatigue.
Mr. Xu, a white-collar worker in Guangzhou (28 years old), was busy rushing a project and sat in an air-conditioned room all day, drinking less than two cups of water. One afternoon, he suddenly felt a heavy head and blackened vision, and after being sent to the hospital for examination, he realized it was caused by mild dehydration.
Medical advice indicates that daily water intake in summer should be maintained at over 2000ml. If working in an air-conditioned room for long periods, one should also drink water every hour. Additionally, beverages like coffee and milk tea, while hydrating, contain diuretic components that can accelerate fluid loss.
Invisible Pollutants in Air Conditioning
Many people are unaware that if air conditioning units are not cleaned and maintained in a timely manner, they can become the "hidden culprit" behind headaches.
If the internal filtering system of the air conditioner accumulates dust, mold, or bacteria, the cold air blown out may carry irritating particles. Once inhaled, these particles can cause inflammation of the nasal mucosa, dry eyes, and even allergic headaches. This pollution is particularly likely to lead to "air conditioning headaches" for sensitive respiratory individuals, such as asthma and chronic rhinitis patients.
Ms. Zhu, a primary school teacher in Beijing (35 years old), experiences headaches every summer when the air conditioning is turned on. Initially, she thought it was due to her cold constitution, but later, upon inspection of the office air conditioning system arranged by her company, she found that the filter was contaminated with excessive mold. After replacing the filter and thoroughly cleaning it, her headache symptoms significantly improved.
Scientists have also pointed out that when air conditioning operates in a closed environment, it can cause an increase in indoor carbon dioxide concentration, reducing the oxygen content in the air. This "mild hypoxia" can also affect the brain's oxygen supply, leading to decreased attention and the occurrence of headaches.
Prolonged Sitting with Head Down Causes "Cervicogenic Headaches"
In air-conditioned rooms, sitting for several hours is the norm for modern office workers. However, this continuous head-down posture or poor sitting position is quietly triggering a type of headache that is often misdiagnosed—cervicogenic headache.
Cervicogenic headaches are not due to lesions in the brain itself, but rather pain radiating upwards caused by tension in the neck muscles and misalignment of the cervical joints. This type of headache is commonly felt in the back of the head and near the occipital bone, and some people may also experience shoulder stiffness, numbness in the hands, or a feeling of heaviness in the head.
Mr. Chen, an IT engineer in Shenzhen (34 years old), sits in front of a computer for 8 hours a day, with the air conditioning blowing directly on his neck. After a few weeks, he developed persistent pressure in the back of his head, and massage was ineffective. He was eventually diagnosed with "cervicogenic muscle tension-type headache" in the rehabilitation department. The doctor advised him to adjust his sitting posture and use a neck support pillow, and his symptoms gradually alleviated.
Office workers should get up and move every 45 minutes, stretch their neck muscles, and avoid direct air conditioning blowing on the head and neck area, which is key to preventing this type of headache.
Disruption of Sleep and Circadian Rhythm
Hot weather often affects sleep quality, and the disruption of circadian rhythms in an air-conditioned environment can further weaken the body's regulatory capacity, becoming a hidden trigger for headaches.
In summer, many people are accustomed to sleeping with the air conditioning on all night, which leads to reduced deep sleep due to low room temperatures; or they may take a nap at their desks, putting excessive pressure on their necks, resulting in worsened headaches upon waking. These all fall under "sleep-related headaches."
Disruption of sleep can also affect the secretion rhythm of melatonin and cortisol, leading to a disturbance in the brain's excitation and inhibition mechanisms, thereby increasing the risk of headache attacks.
A university student, Xiao Huang (22 years old), frequently stayed up late playing games during the summer vacation, had irregular daytime sleep, and kept the air conditioning on all night. He experienced frequent headaches, drowsiness, and decreased attention, and was diagnosed with neurogenic headaches caused by sleep rhythm disorders. By adjusting his schedule and engaging in moderate exercise during the day, Xiao Huang's headaches gradually decreased.
The key to good sleep in summer is to maintain a regular schedule, avoid screen light one hour before bed, keep the room temperature between 25-27°C, and use a timer to prevent the air conditioning from running all night.
Intervention Suggestions: Identify Types and Treat Accordingly
In the face of summer headaches caused by such "invisible culprits," the most effective intervention is not painkillers, but rather "identifying the type and removing the triggers."
If symptoms frequently occur in scenarios of temperature changes, avoid frequently moving between environments with large temperature differences;
If accompanied by dry mouth and fatigue, consider dehydration as a priority and rehydrate accordingly;
If discomfort occurs every time the air conditioning is turned on, check the cleanliness of the air conditioning system and improve ventilation;
If there is pressure in the back of the head and prolonged sitting at work, pay attention to cervical health and adjust sitting posture;
If headaches recur upon waking in the morning, check sleep quality and circadian rhythm.
Additionally, maintaining appropriate outdoor activities, a balanced diet, and limiting the frequency of cold drink consumption can also greatly benefit headache relief.