Mr. Tunc Tiryaki, Founder of the London Regenerative Institute, has shared his advice for overcoming cross-time zone tiredness. Adjust your schedule before travelling. Jet lag occurs when your internal body clock (circadian rhythm) is disrupted due to travelling across multiple time zones. "Shifting your sleep schedule to match the destination's time zone a few days before you travel can be hugely beneficial in helping your body adapt to the new time zone - it won't be as shocking to the system!" Adjust your watch and devices.