The problem with flying a lot
If you cross time zones for work or family more than four times a year, the unaided rule of “one day per time zone” is not just inconvenient, it is half your year. A typical New York to Asia round trip can cost five to seven productive days each way at the unaided rate. Most frequent flyers absorb this as background. Some try Timeshifter and find it useful but narrow. Some never find a system that fits the actual shape of their travel.
Circa is for people who fly often enough that an annual plan that costs less than one airport coffee a day pays for itself in a single trip.
Why this is different
It runs the whole trip. Light, sleep, caffeine, melatonin, exercise, meal timing, hydration, supplements, transit logistics, alcohol mitigation, cabin advice. Most jet-lag apps cover the first two.
It adapts to your real life. You cannot nap at 14:00 if you are in a meeting. You cannot sleep on a 4-hour layover. You cannot block all light when your hotel room faces east. The plan flexes around the constraints.
It treats round trips as one trip. The phase state of your body clock when you land home is different from where you started. Circa models that.
The science is real. A unit-tested engine. Recommendations graded by evidence strength. We tell you what is settled science (light, melatonin, sleep, caffeine), what is supportive (exercise, meals, hydration), and what is comfort-tier (sleep masks, mouth tape).
Pricing
First plan free, always. HK$149 a year for unlimited trips. HK$38 per trip if you only fly once or twice a year. There is no lifetime tier and no monthly grift.
What you might want to read first
- How long does jet lag actually last? The science of recovery.
- The science page. The model, the levers, the honest evidence grading.