Jet Lag Recovery Calculator

According to research published in the Journal of Physiology (Waterhouse et al., 2007) and summarised by the Sleep Foundation, jet lag typically takes one day of recovery per time zone crossed when travelling eastward, and approximately 0.67 days per time zone when travelling westward. Eastward travel is generally harder because it requires advancing the circadian clock (shortening the day), which is more difficult for the human body than delaying it.

The human circadian rhythm has a natural period slightly longer than 24 hours. This makes it easier to delay the clock (stay up later, as required when travelling west) than to advance it (go to bed earlier, as required when travelling east). Research published in Nature Communications (Bhattacharyya et al., 2020) confirms this asymmetry in human circadian adaptation.

Evidence-based strategies from the American Academy of Sleep Medicine include: exposing yourself to bright light at the appropriate time (morning light for eastward travel, evening light for westward), avoiding naps longer than 20 minutes on arrival, adjusting meal times to the local schedule, staying hydrated, and using melatonin (0.5 to 5 mg) taken at the destination's bedtime as a phase-shifting aid, if approved by a doctor.

Yes. Older adults typically experience more severe and longer-lasting jet lag than younger adults. Research suggests circadian adaptability declines with age, and older travellers may require 20% to 50% longer to fully adjust after major time zone transitions. Individuals over 60 are advised to allow extra recovery time before important events.

Most research considers crossing 3 or more time zones sufficient to cause clinically significant jet lag symptoms. Crossing 5 or more time zones (such as a transatlantic or transpacific flight) typically causes moderate to severe jet lag. Crossing 10 or more time zones (such as a flight from the US East Coast to Asia) causes the most severe jet lag and longest recovery times.