Jet lag is a performance tax
For an athlete crossing time zones for a race, training camp, or competition, jet lag is a measurable hit to power output, reaction time, recovery, and sleep quality. The published research on Major League Baseball travel and on US college teams finds reliable performance decrements lasting several days after an east-west flight. The decrements are larger eastward than westward, larger when the trip is short (the body never catches up), and larger when the protocol is left to chance.
Circa is built for athletes who already think in terms of protocol. Sleep matters, light matters, meal timing matters, hydration matters, and the recovery cost of getting any of these wrong is real.
What you get
A personalised plan that aligns light, sleep, caffeine, melatonin, exercise, meal timing, and hydration to your travel. Workouts placed at the time of the destination day that supports the circadian shift, not at a time that fights it. Light scheduled relative to your core body temperature minimum, not relative to local hours. Caffeine cut off in time to protect the sleep window before competition.
The engine treats exercise as a phase-shifting zeitgeber, not just a fitness activity. The placement matters.
What it is not
Circa is not a banned substance. Melatonin is not on the WADA prohibited list at the time of writing. We make no claim that any supplement we recommend will improve performance beyond what the science supports, and every recommendation is graded by evidence strength. If you are subject to drug testing, talk to your team doctor before starting any supplement. We default to extreme honesty.
Pricing
First plan free. HK$149 a year for unlimited trips. HK$38 per trip.
A note on the science
The engine implements a two-process model of sleep and a phase-response-curve model of light and melatonin. Every recommendation is unit-tested across hundreds of routes and traveler profiles. If you want the deeper read, see the science page.