Beat jet lag, before you fly.
Pick origin + destination. Get a severity score, expected recovery time, and a personalised 3-day pre-flight schedule — bedtime shifts, light exposure, melatonin timing. Built on the evidence base from our Jet-Lag Severity Index.
How the planner works
The planner combines two evidence bases: our Jet-Lag Severity Index (for the severity score) and the peer-reviewed adjustment-schedule logic from Eastman & Burgess (2009) and Waterhouse et al (2007). For any city pair across 48 major travel cities, it computes time-zone shift, direction, hemisphere crossing, expected recovery time, and a per-day pre-flight plan.
The core strategy: advance your circadian rhythm before eastward travel, delay it before westward travel. The body's circadian period is approximately 24.18 hours (Czeisler et al., 1999), which means extending days (westward) aligns with natural drift; compressing days (eastward) requires active resynchronisation. The practical consequence: eastward travel typically requires more preparation and more recovery than an equivalent westward flight.
The three tools that matter most, ranked by effect size: (1) timed bright-light exposure at destination-morning (eastward) or destination-evening (westward) is the single most-effective countermeasure — 30-60 minutes of direct sun on day 1 of arrival resets more circadian phase than any other intervention; (2) pre-flight bedtime shifts of 1 hour per day for 3 days in the direction of travel; (3) low-dose melatonin (0.3-0.5mg — NOT the 3-5mg widely marketed, which is supra-physiological) for eastward travel only.
This is a general-guidance tool. Consult a sleep-medicine clinician for persistent insomnia, if you take medications that affect sleep (SSRIs, benzodiazepines, beta-blockers can interact), or if you have a shift-work sleep disorder pattern.