☀ Sundial How it works

Beat jet lag with light, not luck.

Tell Sundial your flight and your usual sleep hours. It builds an hour-by-hour plan — when to seek bright light, sleep, eat, and stop the coffee — grounded in the peer-reviewed circadian science, so your body arrives on local time sooner.

No time to prep? Leave this at 0 — you'll get a plan that starts the day you travel. Every day you can pre-shift (up to 3) is the single biggest head start you can give yourself.

Fine-tune — your sleep habits & options
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How Sundial works

Your body clock doesn't jump time zones — it re-entrains gradually, and the most powerful lever is light at the right time. The pivot is your core body-temperature minimum (CBTmin), about 2½ hours before you normally wake. Light after that point pulls your clock earlier; light before it pushes it later. Sundial estimates your CBTmin from your sleep hours, works out whether to shift earlier (advance) or later (delay) — and by how much — then rolls the whole schedule forward day by day.