Everything we get asked.

Circa generates a personalised, hour-by-hour plan for a flight you are about to take. It covers light timing, sleep, caffeine, melatonin, exercise, food, hydration, supplements, transit logistics, and alcohol mitigation. Every recommendation explains why when you tap it.

Timeshifter is excellent at light and melatonin. Circa runs the whole protocol: exercise placement, meal timing, hydration, supplements, transit, illness-prevention, alcohol mitigation. The lever stack we own is the differentiator. Many of our early users come from Timeshifter and keep both for a while before settling on Circa.

Yes. The engine treats the return as part of the same trip and carries the phase state. Plans for the homebound flight take into account where your body clock actually is when you land, not where it started.

Manual entry today; integrated itinerary import in a later release. The engine handles the multi-leg math; the UI for it is incremental.

Yes. Re-generate the plan with the new flight details and the engine recalculates. We are also working on automatic re-planning from your calendar in a later release.

First plan free, always. HK$149 a year for unlimited trips, or HK$38 per trip if you fly only once or twice a year. There is no lifetime tier and no monthly tier. Annual is the obvious value for anyone flying more than three times a year.

Circa makes its money on annual subscriptions and on affiliate commission from physical products the plan recommends. We deliberately undercut Timeshifter because we want as many people as possible on the protocol. The unit economics work because most users renew.

Yes. A credit unlocks the full premium plan for one trip with no limitations. If you fly more than three times a year, an annual is cheaper.

Subscriptions are handled by Apple, so refunds go through your App Store account. Apple has a standard 14-day return window in most regions.

No. The free first plan is genuinely free. The paywall appears when you go to save a second plan or use a premium lever.

Yes. The engine is built on the two-process model of sleep and the phase-response-curve model of light and melatonin. Both are widely accepted in the circadian-biology literature. Every recommendation is graded by evidence strength: Core, Supportive, or Comfort.

No. Circa is a wellness tool, not a medical device. We do not diagnose, treat, cure, mitigate, or prevent any disease. The plan is general wellness guidance grounded in published science.

No. Circa does not recommend prescription medications. We do recommend low-dose melatonin (over-the-counter in most regions) where appropriate; if melatonin is not over-the-counter where you are, the plan adjusts.

For short-term use at low doses (0.3 to 1 mg) timed against the circadian phase, melatonin is well-tolerated for most adults. We are explicit that it is a chronobiotic, not a sedative, and that the dose-timing window is narrow. If you are pregnant, on medication, or have a medical condition, talk to your doctor first.

We are recruiting a scientific advisory board with sleep and circadian-medicine specialists. Names will be published when the board is formalised.

Circa is in TestFlight beta. The public App Store launch is planned for later this year. Get on the waitlist for early access.

Yes. iOS comes first. Android follows once we have a stable iOS release. The engine is portable.

Not yet. We are talking to a handful of companies about a per-seat plan with admin dashboard, itinerary import, and aggregate wellbeing reporting. Reach out via the contact page if your company wants to be on that conversation.

If you are a creator who covers travel, biohacking, or performance topics, see our affiliate program page. We pay per paid conversion with a custom App Store discount code for your audience.

Hong Kong. The team is small and the product is bootstrapped.