The basics
London to New York crosses five time zones heading west. When you land at JFK at 3pm local time, your body thinks it's 8pm, so you're running five hours ahead of everyone around you. Westbound travel is generally easier than eastbound, because your body's internal clock runs slightly longer than 24 hours. Delaying your sleep is more natural than advancing it.
Most travellers adjust within 3 to 4 days. Some people barely notice it at all on this route, especially if they land in the afternoon and push through to a local bedtime.
What jet lag feels like on this route
Because you're five hours ahead, the symptoms hit hardest in the evening and early morning.
You'll feel exhausted by 7 or 8pm New York time (midnight London time), which means you might crash early and then wake at 3 or 4am wide awake, because your body thinks it's 8 or 9am. This early waking is the signature of westbound jet lag on this route. It usually sorts itself out within two to three nights.
Daytime performance is usually fine. You might feel a slight afternoon dip, but nothing severe. The bigger risk is social: if you're meeting people for dinner, you might be fighting to stay awake by dessert.
Day-by-day recovery plan
On arrival day, if you land in the afternoon (most London to New York flights do), stay awake until at least 9pm local time. Get outside. Natural light in the afternoon helps push your clock later. Avoid napping, or if you absolutely must, keep it under 20 minutes before 3pm. Have dinner at a normal New York time even if you're not hungry.
On day one, you'll probably wake early, around 4 or 5am. That's fine. Don't lie in bed fighting it. Get up, have a quiet start, and get outside once the sun's up. Morning light helps here. You might feel great until mid-afternoon, then hit a wall around 3 or 4pm. Push through. Aim for a 10pm bedtime.
On day two, the early waking should shift later, maybe 5:30 or 6am. Keep seeking morning and afternoon light. By the evening you should be able to stay up comfortably until 10 or 11pm. Most people feel 80% normal by the end of day two.
By day three, most people feel normal. Your sleep should be close to your usual pattern. If you're still waking early, a small dose of melatonin (0.5 to 1mg) taken at 10pm local time can help nudge your clock the last bit.
What helps
Light exposure is the single most effective tool. On this route, you want afternoon and evening light on your first day or two. This tells your brain that the day is longer than it expects, which pushes your clock later.
Melatonin can help if you get the timing right. A low dose (0.5 to 1mg, not more) taken at your target bedtime in New York supports the shift. Take it 30 minutes before you want to sleep.
Caffeine is fine in the morning and early afternoon, but cut it off by 2pm local time. You're already prone to early waking, and caffeine late in the day makes it worse.
Avoid alcohol on the flight and the first night. It might help you fall asleep but it fragments your sleep and worsens the early-morning waking.
What to avoid
Don't try to pre-adjust your sleep schedule in London before you fly. A five-hour shift isn't practical to simulate at home while still functioning at work. The adjustment is easier done on arrival.
Don't nap for hours on your first afternoon. A long nap resets your clock to London time and undoes your progress.
Don't stay in your hotel room. Daylight is the mechanism that resets your clock, not willpower.
The return trip
Coming back is harder. London-bound you're flying east, crossing the same five zones but now you need to fall asleep earlier and wake earlier. Expect 4 to 5 days of adjustment. Eastbound jet lag shows up as difficulty falling asleep at night and grogginess in the morning.
Get a plan for your exact flight
The general advice above works for most people, but your ideal recovery plan depends on your specific flight time, sleep habits, and trip length. Our free planner builds a personalised schedule based on your details.