Jet Lag Calculator
Crossing time zones disrupts your body's internal clock. Use this calculator to get a personalized recovery plan — including exactly when to seek or avoid bright light and when to take melatonin — so you can feel like yourself again as fast as possible.
Jet Lag Calculator
Plan your recovery with personalized light and melatonin timing
Typically 1 zone per hour of flight time difference
How the Jet Lag Calculator Works
Your body's circadian rhythm is governed by light and the hormone melatonin. When you travel across time zones, these signals become out of sync with local time — that's jet lag. The good news is that you can actively retrain your clock using strategic light exposure and melatonin.
Flying East
Eastward travel advances your clock — you need to sleep and wake earlier than you normally would. Seek bright morning light at your destination and avoid evening light for the first few days. Take a low-dose melatonin (0.5–1 mg) at the local bedtime. Expect roughly one day of adjustment per time zone crossed.
Flying West
Westward travel delays your clock — you'll feel alert too late at night and groggy in the morning. Seek afternoon and early-evening light, avoid morning light for the first few days, and stay awake until local bedtime. Western travel is generally easier, adjusting at about 1.5 hours per day.
Light Exposure
Light is the most powerful zeitgeber (time cue) for your circadian rhythm. Morning light shifts your clock earlier; evening light shifts it later. Even 30 minutes of outdoor sunlight or a 10,000-lux light therapy lamp can make a meaningful difference.
Melatonin
At low doses (0.5–1 mg), melatonin acts as a chronobiotic — it signals to your brain that it is nighttime, helping to shift your sleep timing. Take it at your destination's bedtime, starting the night before you depart for maximum effect.