Sleep on the Plane or Stay Awake?

Sleep on the plane during the hours that are night where you are going; stay awake during its daytime. A 7:00 PM New York to London flight is night in London almost the whole 7 h 11 min; an 11:00 AM London to New York flight, only the first hour. Staying 2 nights or fewer? CDC suggests your home clock.

How to use it

Type your two airports, the day and time you take off, and when you usually go to bed and wake up. The answer splits the flight into stretches: sleep while it is your usual night on your destination's clock, stay awake while it is daytime there. The bar shows the flight from takeoff to landing, night dark and day light, and the list under it gives each stretch in destination time and in hours after takeoff. Tick "Staying 2 nights or fewer" and the plan uses your home clock instead. The link under the answer keeps every choice.

Why the destination's clock

CDC's Yellow Book: Jet lag results from a mismatch between a person’s circadian (24-hour) rhythms and the time of day in the new time zone. And for a trip of more than two days: A traveler staying in the time zone for >2 days should quickly try to adjust to the local sleep–wake schedule as much as possible. Sleeping in the destination's night, already on board, is the first step of that. For a short trip CDC says the opposite: If a traveler spends ≤2 days in the new time zone, they might prefer to anchor their sleep–wake schedule to the time of day at home as much as possible.

Direction matters too. Eastman and Burgess, the sleep researchers whose model the Jet Lag Calculator uses: Flying east requires a phase advance of the circadian clock, and flying west requires a phase delay. As mentioned above, it is easier for most people to phase delay than to phase advance. That is why an evening flight east asks you to sleep at once, and a daytime flight west asks you to stay up.

The time in the air is the Flight Time Calculator's estimate of a scheduled non-stop between your two airports, and every local time follows your browser's time-zone rules on the day you fly, daylight saving included.

Worked examples

• New York to London, leaving 7:00 PM: takeoff is 12:00 AM in London and you land at 7:11 AM. Sleep almost all of the 7 h 11 min; the last 11 min are London's morning.
• London to New York, leaving 11:00 AM: takeoff is 6:00 AM in New York. Sleep the first hour if you can, then stay awake 6 h 48 min and land at 1:48 PM ready for an early night.
• San Francisco to Sydney, leaving 10:30 PM: takeoff is 5:30 PM in Sydney. Stay awake 5 h 30 min, sleep 8 h through Sydney's night, then stay awake the last 2 h 20 min before a 9:20 AM landing.
• New York to London for two nights: on your home clock the same 7:00 PM flight is 4 h awake and 3 h 11 min asleep, landing at 2:11 AM New York time.

Which takeoff time lets you sleep most

Under the answer, the same route at every hour of the same day: how much of the flight is your night on the clock you sleep by, and when you land. The hours with the most night on board are starred; tap one to see its plan. A red-eye east usually wins, and a flight west usually has its night only at hours few airlines fly — then pick the real flight with the most night, or plan to stay awake. On November 15, 2026, with a usual night of 11:00 PM – 7:00 AM:

The landing column is for the first of the starred hours. On a short flight a red-eye can put the whole flight in your night and still land you at 4 AM: the grid shows the landing beside every hour so you can weigh both.

Common mistakes

• Sleeping by your watch. A 7:00 PM takeoff feels like evening, but it is midnight in London: the evening is already over where you are going.
• A drink to fall asleep. CDC: Travelers should not use alcohol as a sleep aid, because it disrupts sleep and can provoke obstructive sleep apnea.
• Trusting melatonin to fix it. CDC says two US health bodies suggest that melatonin could be used to reduce symptoms of jet lag, with a caution about other medicines; the NHS: Melatonin tablets are not recommended on the NHS for jet lag because there's not enough evidence to show they work. Ask your doctor before you take any.
• Calling a short hop jet lag. CDC: For travelers crossing ≤3 time zones, especially if they are on a long-haul flight, symptoms (e.g., tiredness) are likely due to fatigue rather than jet lag, and symptoms should abate 1–3 days post-flight.

After you land

The Jet Lag Calculator plans the days after landing, when to seek daylight and when to avoid it. The NHS keeps it simple: go outside during the day – natural light will help your body clock adjust. On the Flight Time Calculator, "Plan my long-haul hours" writes the whole first day hour by hour. Our long flight survival guide and how to arrive functional after a red-eye cover the flight itself, and what to pack for the plane the mask, earplugs and layers that make sleep possible.