How the FlySalah sleep plan works

What the plan does

Before you fly, it moves your bedtime toward the new time zone, 1 hour a day, for 1 to 3 days. On the plane and after landing, it tells you when to sleep, when to seek light, and when to stop caffeine. Prayers come first.

Your body clock

Your body keeps a 24-hour clock, set mostly by light. After a big flight it stays on home time. On its own it moves about an hour a day. The plan assumes about an hour a day. It does not promise a number of days saved. People differ.

Three levers

Light is the strongest signal to your body clock. Morning light moves it earlier. Evening light moves it later.^{S2, S6}
Sleep timing. Move your sleep toward the new time before you go, then keep to it.
Optional: melatonin and caffeine timing.

Why you sometimes avoid light

Light at the wrong time can slow or reverse the shift. So the plan has you dim light and wear sunglasses at set times. The right times depend on your direction of travel and your body clock, so follow the times the plan shows.^S6

Before you fly

Shifting your sleep 1 hour a day before you fly gives your body clock a head start of up to 3 hours, so there is less to adjust after landing. The plan sets how many days you need, from 1 to 3, by the size of the shift. Trips under 1.5 hours of shift need none. The researchers behind this method recommend shifting no more than about 1 hour a day.^S6 Any head start is better than none.

What research says

This table shows planning figures from the research. It is not what the app saves, and the app does not use the faster rates.

	East	West
On its own	about 1 hour a day	about 1.5 hours a day
With timed light, as modelled in research	about 1.5 hours a day	about 2 hours a day

Sources:^S2 for the first row,^S6 for the second. These are estimates. "Adjusted" can mean your body clock, your sleep or how you feel, and people differ. Real travellers in one study moved a little less than the models: about 57 minutes a day east and 92 minutes west.^S6

Around your prayers

Prayers come first. If a prayer falls in a sleep block, it shows inside the block with a reminder. If Isha is just before bed, the plan says "Pray Isha, then sleep".

Melatonin

What it is. Melatonin is a hormone your body makes in the evening. It tells your body clock that night has started.^S3

Why it is optional. It is a timing signal, not a strong sleeping pill. Studies are mixed. A Cochrane review found it helps most across five or more time zones, especially going east.^S1 In its 2007 guidance, the American Academy of Sleep Medicine recommended it for jet lag, taken at the right time.^S7 The NHS does not recommend it for jet lag, saying there is not enough evidence that it works.^S4 That is why the plan is built on light and sleep first, and melatonin is optional.

How much. The plan shows 0.5 mg, a low dose. The plan uses the low dose because the CDC says 0.5 to 1 mg is often enough to shift your body clock, and it is less likely to leave melatonin in your body at the wrong time of day.^S2 Ask a pharmacist or doctor which product and dose suit you. If only a higher dose is sold where you are, ask the pharmacist; studies found 0.5 to 5 mg similarly effective, with 5 mg helping people fall asleep faster.^S1 There is no extra benefit above 5 mg.^S1 If you miss a dose, do not double up.

When. Take it close to your new bedtime, at the time the plan shows.^S1 Taken at the wrong time of day, it can make adjusting harder. If you miss the time, skip it that day rather than taking it late.

For how long. Only on the days the plan shows, around the trip. Stop when the plan stops. Short-term use looks safe for most people. Long-term safety is not known.^S3 On trips where the plan shows no melatonin, light does the work.

Where to get it. Rules differ by country: a supplement in some, a prescription medicine in others, not sold in a few. Check before you travel and ask a pharmacist there. Label amounts can also be wrong.^{S2, S3}

Halal. Melatonin itself is not the issue. Some capsules use gelatin.^S15 Pick a tablet, a gelatin-free capsule, or a product with a halal certificate from a body you trust. For a ruling, ask a scholar.

Who should ask a doctor first. Ask a doctor first if you are pregnant or breastfeeding, have epilepsy or a sleep disorder, take blood thinners, blood pressure or diabetes medicines, or have an immune condition. Ask too for children, teens and older adults.^{S1, S3}

Side effects. Side effects are usually mild: sleepiness, headache, dizziness, nausea.^S3 Do not drive if you feel drowsy.

Caffeine

Why a cut-off. Caffeine stays in your body for hours; the plan counts about 6 hours. Its half-life is about 5 hours and differs between people.^S2 So the plan sets a last-coffee time 6 hours before your target bedtime. In one study, a large dose (400 mg) taken 6 hours before bed cut measured sleep by about an hour.^S17

How much is in a drink. About: brewed coffee (237 ml) 96 mg, espresso shot (30 ml) 63 mg, black tea (237 ml) 48 mg, cola (237 ml) 33 mg, small energy drink (237 ml) 79 mg. Real amounts vary a lot.^S18 The FDA gives 113 to 247 mg for a 355 ml coffee.^S19

How much per day. Health agencies say up to 400 mg a day for healthy adults. In pregnancy, keep to 200 mg a day.^{S19, S20} Ask a doctor if you are breastfeeding or have a heart condition.

Using it. Before the cut-off, a coffee or tea in your destination daytime can help you stay awake when the plan wants you up. The CDC suggests 200 mg every 4 hours during daylight, stopping 6 hours before bed.^S2 Stay within the daily limit. Do not lean on it. It hides tiredness and does not repay lost sleep.

Fasting and Ramadan. If you are fasting in Ramadan, caffeine fits only between iftar and suhoor. The cut-off still applies. If it falls before iftar, skip caffeine that day.

Not medical advice

General guidance, not medical advice. Ask a pharmacist or doctor if you are pregnant, take medicines or have a health condition.