How to Actually Sleep on a Long-Haul Flight

Twelve hours over the Pacific, and one lever that matters more than all the others.

There is a particular hour on every long-haul flight out of New Zealand, somewhere over the Pacific, cabin lights dimmed, half the plane already gone, when you realise everyone around you is asleep and you are not. For a country that lives further from everywhere than almost anyone, and tends to flee the July cold in its thousands, it is close to a national predicament. Twelve hours to London via somewhere, and you land creased, hollow and three days behind yourself.

Most of getting it right comes down to one thing we consistently underestimate. Light.

In short

• Darkness is the lever. Light reaching your eyes suppresses melatonin, the hormone that tells your body it is night.
• A dimmed cabin is not dark. Screens, galley light and a lifted window shade are all still reaching you.
• Cabin air sits below 10% humidity, drier than most deserts, which is its own problem for skin and sleep.
• A proper eye mask, something warm, something for the noise, and water rather than the second wine.

Why darkness is the lever

Your body decides when to feel sleepy largely by how much light reaches your eyes. Specialised receptors in the retina report light levels straight to the brain's master clock, which in turn governs melatonin, the hormone that ushers in sleep. Light suppresses it. Darkness permits it. This is among the most settled findings in sleep science, and it is the reason a red-eye feels so much easier once the cabin finally goes dark.

The trouble is that a dimmed cabin is not a dark one. There is the seat-back screen two rows up, the galley glow, the reading light of a stranger who has decided 2am is the moment for a novel, and the neighbour who lifts the window shade somewhere over the Tasman. Take that light away properly and you remove one of the main reasons your brain is refusing to switch off.

How much does a mask itself buy you? Here it is worth being straight with you. A 2023 study in the journal Sleep reported that a week of wearing an eye mask overnight improved memory encoding and next-day alertness. It was a genuinely interesting result, and it made headlines. It was also challenged the same year by a reanalysis published in the same journal, which found the evidence less clear than first reported. So the honest position is that the specific cognitive claims are still being argued over.

What is not in dispute is the mechanism underneath. Light reaches your eyes, melatonin drops, sleep is harder to find. On a plane, where genuine darkness is otherwise impossible, a mask is simply the most reliable way to create it. You do not need a contested study to justify it. You need only to have tried sleeping next to an open window shade.

The other thing nobody warns you about

Somewhere above about ten thousand metres, the air in the cabin becomes extraordinarily dry.

Cabin air is drawn from outside, and at altitude there is almost no moisture in it. Relative humidity in the cabin typically falls below 10% within a couple of hours of take-off and stays there, which is drier than most of the world's deserts. Your skin notices before you do. Researchers measuring skin hydration on long-distance flights found that surface hydration drops rapidly and measurably over the course of a flight, as water simply evaporates from the skin into air that has room for it.

That is why you land with tight, papery skin and a headache you cannot explain, and it compounds the sleep problem. Dry air irritates the nose and throat, which wakes you. So the sensible responses are dull and effective: drink water steadily, skip the second glass of wine, and do not let anything on your face wick away what little moisture you have left. Cotton and cheap synthetics are absorbent. Silk, being a smooth protein filament, is far less thirsty, which is exactly why we make the case for silk against the skin generally, and why it is a better choice pressed against your face for twelve hours.

Why the mask itself matters

Not all of them are equal, and the sateen freebie in the amenity kit is usually the problem. It slides, it presses, and it goes damp.

A good mask blocks light completely without pressing on your eyes, and stays put when you turn your head against the window. This is where silk quietly earns its place. A silk eye mask is light enough that you forget you are wearing it, breathable in a stuffy cabin rather than sweaty, and gentle on the thin skin around the eyes. No elastic trench across your face at customs, and nothing dragging at lash extensions. The full case for silk over the eyes holds on the ground. At thirty-eight thousand feet it holds rather more.

The rest of the kit

Darkness does the heavy lifting. A few honest companions do the rest.

Sound. Noise-cancelling headphones, or simple foam plugs, turn engine roar into a floor of white noise you can sleep on top of.

Warmth. Cabins run cold on purpose. A large silk or wool-blend scarf doubles as a wrap and, knotted right, a passable pillow.

A cue, not a pill. Keep whatever tells your body it is night. The same podcast, a hand cream you only smell on planes, socks off, screen away. Routine is the signal.

Water, and skip the second wine. Dry cabin air and alcohol both fragment sleep. Boring, and true.

Your own pillowcase. This sounds excessive until you have done it. A travel-size silk pillowcase weighs almost nothing, slips over the flat airline pillow, and means your face spends the night against something clean and smooth rather than laundered polyester.

If you are assembling this for someone else, our silk gift sets pair the mask with a scarf, which is most of the kit in one box. And if you would like our one-page long-haul checklist to pack against, add your email below.

None of this cures the strangeness of hurtling across time zones in an aluminium tube. But get the light right, add a little warmth and quiet, and you give your body the one thing it has been asking for since take-off, which is permission to believe it is night. Somewhere near the far end of a New Zealand winter, that is the difference between arriving wrecked and arriving ready. Pack the mask on top, not at the bottom.

Frequently asked questions

How can I sleep better on a long-haul flight?

Block the light first, because that is the single biggest lever. Add ear plugs or noise-cancelling headphones, something warm, and a consistent wind-down routine. Drink water steadily and go easy on alcohol, which fragments sleep more than most people realise.

Do eye masks actually work on planes?

They work by creating darkness, which lets melatonin rise. That mechanism is well established. Some specific claims about masks improving next-day memory are still debated among researchers, but for the practical purpose of falling asleep in a lit cabin, a mask is the most reliable tool you have.

Why is a silk eye mask better for flying?

Cabin air is very dry, and silk is far less absorbent than cotton or synthetics, so it does not wick moisture from the delicate skin around your eyes. It is also lightweight and breathable in a warm cabin, and gentle enough to leave no crease across your face when you land.

How dry is the air on a plane?

Cabin humidity typically drops below 10% within a couple of hours of take-off and stays there for the rest of the flight, which is drier than most deserts. This is why skin, eyes, nose and throat all feel parched by the end of a long flight.

Should I take my own pillowcase on a flight?

It is a small thing that makes a surprising difference on overnight flights, especially in a lie-flat seat. A travel-size silk pillowcase packs down to almost nothing and gives you a clean, smooth surface against your face for the whole night.