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Your body is still on the last time zone
Flying east costs you more than flying west, and no amount of willpower changes the exchange rate. Your watch says 08:00 and everything inside you disagrees.
In short
You landed, you are on local time on paper, and your body is running four or eight hours behind. Wide awake at 3am, unusable at 3pm, and it lasts roughly a day per time zone.
- day per time zone, roughly, going east
- 1day per time zone, roughly, going eastWestward usually settles faster than that
- sounds for a room you have never slept in
- 63sounds for a room you have never slept in
- languages, wherever you land
- 33languages, wherever you land
East is harder than west, and it is not close
Left alone, the human body clock runs slightly longer than 24 hours, so stretching a day is easier than shortening one. Flying west asks you to stay up later, which you are built to do. Flying east asks you to fall asleep earlier, which you are not.
The rough exchange rate is about a day of adjustment per time zone going east, and rather faster going west. Six hours east is most of a working week. The same six hours west is a couple of slightly odd days.
Light timing is the lever, everything else is support
Light is what actually moves the clock, and the timing matters more than the amount. Getting it backwards will push you the wrong way and make the whole trip worse, which is the part most jet lag advice skips.
- Set your watch and your phone to destination time when you board, and start thinking in that clock straight away.
- Going east, seek light in the destination morning and avoid it in the destination evening.
- Going west, do the opposite: light in the local evening, and do not force yourself up into a dark morning.
- After a very long eastward hop, avoid bright light in the first hour or two of the local morning for the first day, then chase it. Too early and you push the clock the wrong way.
- Eat on local time from the first meal. It helps and it costs nothing.
- Naps under thirty minutes only, and not in the late afternoon.
- Before you take melatonin or anything else for a flight, ask a pharmacist or a doctor.
Where Tock actually helps
Honestly: it is a support act here. What it does well is the part where you cannot afford a mistake. A hotel room, a phone that has been on silent since the gate, a Focus you set on the plane, and a 05:00 airport run. Tock is built on AlarmKit, so the alarm rings through all of that on the native full-screen alert, and a mission means you do not dismiss it in a fog and lose the flight.
The rest is knowing whether you are over it. Tracking a week of nights shows the clock moving, and that is more useful than guessing on day three whether you feel bad because of the time zone or because of the hotel mattress. Sixty-three sounds help with the second one.
Tock has no jet lag plan built in. It will not schedule your light exposure for you.
The parts of Tock that apply to you
Not all of it will. These are the ones that do something specific about the problem above.
- Alarm on silentA hotel room, a phone muted since the departure gate, a Focus you set on the plane, and a 05:00 transfer. The alarm rings through all of it on the full-screen alert.
- Sleep soundsAn unfamiliar corridor, a lift you can hear, and a road with a rhythm you have not learned yet. Layer four and raise the floor so the first night is not spent listening to the building.
- Smart wakeThe first mornings after a long eastward flight are the most badly timed wakings you will have all year. The 30 minute window takes some of the edge off a 06:00 that your body thinks is the middle of the night.
- Sleep trackingOver a week you can watch the clock actually move instead of guessing on day three whether you are through it yet.
Where Tock will not help
- Tock does not shift your body clock. Light timing, meal timing and holding the local schedule do that, and no app can make you go outside at the right hour.
- There is no jet lag plan or time zone schedule in the app. It is an alarm and a sleep tracker that happen to be useful while you adjust.
- The first nights in a new room make the phone-only stage estimates noisier, because the phone is on an unfamiliar surface in an unfamiliar building. The totals are the part worth reading.
- Before taking melatonin or a sleeping tablet for a flight, ask a pharmacist or a doctor. Tock is not a medical device and has nothing to say about medication.
Tock estimates your sleep and is not a medical device. Nothing it shows you is a diagnosis, and anything that worries you is a conversation for a doctor rather than an app.
Questions people ask
Why is flying east worse than flying west?
Your body clock naturally runs a little longer than 24 hours, so stretching a day is easy and shortening one is not. West asks you to stay up later, which suits it. East asks you to fall asleep earlier, which does not.
How long does jet lag last?
Roughly a day per time zone going east, and usually faster going west. Getting the light timing right shortens it; getting it backwards can make it last longer than the trip.
Can an app fix jet lag?
No. The lever is light timing, backed up by eating and sleeping on local time from the first day. An app can hold the alarm you cannot afford to miss and show you whether your nights are settling, and that is the honest limit of it.
Should I nap when I land?
A short one, under thirty minutes, and not in the late afternoon. A long nap on arrival feels wonderful and reliably costs you that night, which sets the whole adjustment back a day.
Other situations
The same problem seen from a different bed.
- Night shift workersYou finish at 7am and try to sleep while the sun is up, the neighbours are drilling and your phone is on silent so nothing wakes you. Then you have to get up on time anyway, in the middle of what your body still thinks is the afternoon.
- Rotating shift nursesYour rota moves you from days to nights and back again, sometimes inside the same week, and there is no schedule to settle into because the schedule keeps changing. Every adjustment gets interrupted by the next one.
- Early risersYou are up before your alarm most days, lying there working out whether to get up or risk another twenty minutes. On the days you go back to sleep, you feel worse than if you had just got out of bed.
- Light sleepersYou wake at everything, and then you are awake for forty minutes at 3am doing arithmetic on how much is left. By morning you cannot say what woke you, only that something did, several times.
Elsewhere on the site
A different corner of the same problem.
- AlternativesTock vs CalmTock is not a Calm replacement and does not try to be. Calm has a narrated library with named voices and licensed music that a small team cannot match. Tock wakes you, tracks the night and tells you what happened. If falling asleep is your problem, Calm is the better buy.
- RoundupsThe best alarm apps for shift workersFor shift workers the most reliable alarm is still the iPhone Clock app, because it makes no assumptions about your schedule and lets you keep a saved alarm for every shift pattern. Tock is the better pick if you also sleep in the daytime and need something that will not let you turn it off half asleep at 4pm.
- Wake timesWaking up at 4:30amBedtimes by sleep cycle for a 4:30am alarm.
- BedtimesGoing to bed at 2:00amWhere to put the alarm after a 2:00am lights-out.
- Sleep by ageHow much sleep adults needThe American Academy of Sleep Medicine recommends that adults sleep 7 or more hours per night on a regular basis to promote optimal health. It is expressed as a minimum rather than a range because the evidence supports a lower bound far more firmly than it supports an ideal figure.
- NapsThe coffee napA coffee nap means drinking caffeine and then immediately napping for about 20 minutes. Caffeine takes roughly 20 to 30 minutes to have a noticeable effect, so it does not stop you falling asleep quickly, and you wake as it takes hold. The two effects add rather than cancel.
Start with the moment you get woken
It is the one part of your night you can change tonight. Tock waits for a lighter moment in the last half hour and rings a little early when it finds one.