Winter to summer and vice versa: consequences for the body of different age groups

Introduction: the challenge of chronobiology and adaptation

Quick changes in climate and time zones (jet lag) along with extreme seasonal changes represent a powerful stress for all regulatory systems of the body. This is not just "acclimatization," but a comprehensive restructuring of circadian rhythms, thermoregulation, vegetative tone, and immune response. The consequences of such a transition are fundamentally different for children, adults, and the elderly due to the age-specific characteristics of physiology and adaptive reserve.

Physiological basis of stress: more than just a change in temperature

The body is faced with a triple blow:

Disorientation of circadian rhythms. Disruption of "internal clocks" located in the suprachiasmatic nucleus of the hypothalamus. Melatonin (sleep hormone) production, cortisol (stress and wakefulness hormone), and digestive enzymes are disrupted. The body continues to live in "winter" mode when it's "summer" outside, and vice versa.

Extreme thermoregulatory shock. An emergency reconfiguration of the heat exchange system is required: from working in conditions of cold stress with maximum heat preservation to a cooling mode through sweating and expansion of peripheral vessels, which creates a load on the cardiovascular system.

Immunological provocation. A sharp change in the environment (new allergens, pathogens, temperature) temporarily reduces the effectiveness of the immune response, increasing the risk of respiratory and intestinal infections ("traveler's diarrhea").

Age groups: differentiated risk analysis

1. Children (especially preschool and elementary school age)

The child's body has high plasticity, but its regulatory systems are still immature.

Consequences: Manifestations are bright and fast: sleep disorders (the child confuses day and night), moodiness, disturbances in appetite and digestion, possible fever due to stress. Especially dangerous for babies is the risk of heat stroke during a flight "to summer" due to their imperfect thermoregulatory system and faster dehydration.

Critical fact: Studies show that changes in circadian rhythms in children under 3 years of age caused by changes in more than 2-3 time zones are significantly more pronounced and prolonged than in adults. Their internal "clocks" synchronize slower.

Example: A child who flew from -20°C to +30°C may show weakness and refusal to eat on the first day — this is not just fatigue, but disorientation of the hypothalamus, which controls sleep, appetite, and thermoregulation.

2. Adults (25-50 years)

This group has the maximum adaptive reserve, but the consequences depend heavily on the initial state of health and lifestyle.

Consequences: Classic symptoms of jet lag: insomnia or drowsiness, decreased cognitive functions (attention, memory), irritability, disturbances in gastrointestinal tract function. A flight "to winter" often exacerbates chronic inflammatory diseases (sinusitis, cystitis), while a flight "to summer" may trigger hypertensive crises in people with unstable blood pressure due to sudden vessel expansion and dehydration.

Critical fact: Scientific data indicate that adaptation during a flight to the west (extension of the day) is easier than to the east (shortening of the day). However, a change of season complicates this scheme: a flight to the east "from summer to winter" is a double blow.

Example: A sportsman or a businessperson who has made such a flight may see a significant decrease in endurance, accuracy, and reaction speed for 3-5 days, which is confirmed by objective tests. This is due to a disruption in cortisol production and a violation of neuromuscular coordination.

3. Elderly people (65+ years)

The most vulnerable group due to the age-related decrease in functional reserves and the presence of chronic diseases.

Consequences: The risks are not just uncomfortable, but life-threatening. High probability:

Decompensation of cardiovascular diseases (hypertensive crisis, angina attack, arrhythmia) due to the load on the vessels and changes in blood rheological properties.

Exacerbation of chronic cerebrovascular insufficiency with increased dizziness, ringing in the ears, the risk of transient ischemic attacks.

Severe disruption of sleep and cognitive functions, which may take weeks to recover.

Expressed exacerbation of arthritis and osteochondrosis when traveling to a cold, humid climate.

Critical fact: Studies in the field of chronogeriatrics show that the elderly have reduced endogenous melatonin production, and its receptors are less sensitive. Therefore, the natural adjustment of circadian rhythms after a flight is fundamentally disrupted in them and often requires pharmacological correction.

Example: An elderly person with initial signs of atherosclerosis, flying from a cold winter to a tropical summer, risks experiencing a sudden spasm or, conversely, pathological expansion of the cerebral vessels due to dehydration and pressure fluctuations, which may trigger a stroke.

General recommendations and strategies for mitigating consequences

Preparation (2-3 days before departure): Gradually shift the time of going to bed and meals towards the new zone. Start an adaptogen course (by doctor's prescription), for example, melatonin in small doses.

During the flight: Hydration is the cornerstone. Refrain from alcohol and caffeine. Use compression stockings to prevent venous stasis. Light exercise every 1.5-2 hours.

Upon arrival:

For everyone: Immediate synchronization with local time (if you arrived in the morning, do not sleep but go out into the light, if in the evening — help yourself with melatonin).

For children: A gentle regimen, plenty of fluids, light food. Do not plan active entertainment in the first 2-3 days.

For the elderly: Mandatory blood pressure and pulse control. Delayed start of any activity (postpone tours for 3-4 days). Consultation with a treating doctor about possible therapy adjustments (for example, temporary increase in the dose of antihypertensive drugs).

Conclusion

Flights across several seasons are a serious physiological test, the scale of which depends directly on age. For a young body, this is often just temporary discomfort, but for the elderly, it is a real threat to health, comparable to a severe stress load. Conscious planning of such a trip, taking into account age-specific risks, sufficient time for adaptation, and, if necessary, consultation with a geriatrician (for the elderly) or a pediatrician (for children) — the only way to turn a sharp change from winter to summer into a potentially dangerous event into a manageable adventure.

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