Long-haul flights crossing 6+ time zones disrupt circadian rhythm in ways that affect sleep, cognition, GI function, and immunity. Natural adaptation takes about 1 day per hour of time difference, but strategic light exposure and melatonin can cut that in half. This guide presents a phased protocol covering pre-flight preparation through 3 days after arrival.
Why Jet Lag Happens
Jet lag results from mismatch between internal circadian clocks and external environment (light, meals, social cues).
Core Mechanism
- SCN (suprachiasmatic nucleus) lag: Brain clock adjustment averages 1 day per hour
- Peripheral clock desynchronization: Liver, kidney, and muscle clocks adapt even slower
- Direction matters: Eastward flights (Seoul → LA) are harder than westward — shortening a day is harder than extending it
Symptoms
Insomnia, daytime drowsiness, focus problems, appetite changes, constipation or diarrhea, headaches, muscle aches, mood swings. Usually resolves in 3-7 days but can become chronic for frequent travelers.
Pre-Flight Preparation (3 Days Out)
Gradually shifting toward destination time 3 days before departure makes adaptation much easier.
Eastward Flight (Time Shortening, e.g., Seoul → New York)
- Go to bed 30-60 min earlier each day
- 30 min of morning sunlight within 1 hour of waking
- Avoid evening caffeine and bright light
Westward Flight (Time Extending, e.g., Seoul → Rome)
- Stay up 30-60 min later each day
- Evening sunlight or strong artificial lighting
- Allow morning sleep-ins
Related: Circadian Rhythm Sleep Optimization.
In-Flight and Arrival Care
The in-flight period and the first 72 hours after arrival are critical.
In-Flight
- Hydration: 250ml/hour, avoid alcohol and caffeine
- Sleep: Use eye mask and earplugs during destination night time
- Light movement: Stretch every 2 hours, walk the aisle
First 24 Hours After Arrival
- Light strategy: 30 min of sunlight if morning at destination; stay in darkness if evening
- Meals: Eat on destination time — meals also entrain the clock
- Light exercise: 30-minute walk modulates alertness
NIR LED Supportive Care
For accumulated muscle tension from extended sitting, 850nm NIR LED supportive care may help (Hamblin, 2017). 10 minutes on calves, lower back, and neck may help ease swelling and assist recovery.
Daily Application Guide
Recovery strategy depends on flight length and direction.
Melatonin Use
A low dose (0.3-0.5mg) of melatonin 30 minutes before destination bedtime is effective (Suhner et al., 2001). Avoid high doses like 5mg which can cause next-day grogginess.
3-Day Recovery Schedule
- Day 1: Follow destination schedule, early bedtime
- Day 2: 30 min morning sunlight + light exercise + normal meals
- Day 3: Full activity resumed, 60-80% of jet lag symptoms resolved
If symptoms persist over 7 days or are accompanied by severe depression, seek medical care.
