A letter fromBentota.

By the third morning the body has stopped expecting things. By the fifth, the doctor's plan begins to feel like the only sensible way to spend a day. By the seventh, you find yourself walking more slowly down the corridor than you have walked anywhere in a year, and you are not sure when this happened.

What an Ayurvedic week actually is

It is not a spa, and the distinction matters, because the word has been borrowed by enough hotel treatment menus that most people arrive expecting a massage with better lighting. A serious Ayurvedic programme opens with a consultation instead: pulse, tongue, sleep, digestion, appetite, medical history, and an assessment of constitution, which is what the plan is then written against. Nothing is chosen from a list. The doctor sets the treatments, the order they come in, the oils, and the food, and revises all of it as the week goes on. You are not a guest selecting; you are a patient being read.

The treatments themselves are old and specific, and it helps to know the names before someone says them to you at seven in the morning.

• Abhyanga, a full-body massage with warm medicated oil, usually worked by two therapists moving in time with each other. This is the daily foundation of almost every plan.
• Shirodhara, a continuous thread of warm oil poured across the forehead. It is the one nearly everyone remembers afterwards.
• Swedana, herbal steam taken in a wooden cabinet with the head left out, almost always immediately after oil.
• Pizhichil, warm oil poured over the whole body in a steady stream by hand. Usually reserved for the longer programmes.
• Panchakarma, the full cleansing sequence of which the treatments above are components. It is the part that cannot be compressed, and a doctor offering it inside a few days is not offering it.

The shape of a day

Early, and slower than you want it to be. Herbal tea before six, then yoga or breathwork while it is still cool, then the treatment block, which runs long. Lunch is the largest meal of the day, on the reasoning that digestion is strongest at midday: vegetarian, warm, cooked to your constitution, lightly spiced rather than dull. The afternoon is rest, and it is deliberately unscheduled. A second and shorter treatment before dusk. Dinner early and light. There is no alcohol, no coffee, no cold water, and on most plans no swimming while you are carrying oil. The day has no gaps to fill, which is disorienting for about seventy-two hours and then stops being.

The pavilion is open on three sides. The floor is polished red oxide. The room smells of warm sesame oil and the wood of the ceiling, which has been here since before any of us. Dr Jayasena writes in the morning in a notebook bound with red thread. He reads to you, occasionally, what he has written about you. It is always shorter than you expect.

How long it needs

Longer than most people plan for, and this is the thing worth arguing with us about before you book rather than after. The doctor sets the length once they have seen you, and the number they give is not a sales tactic: the sequence prepares the body, then cleanses it, then rebuilds it, and the rebuilding takes as long as the first two stages together. Compress it and you have not done a shorter version of the same thing, you have done a different thing. A brief stay is a very good rest with unusually thoughtful food, which is a legitimate thing to buy and should simply be called that. Tell us which you are after and we will tell you honestly whether the dates you have in mind can carry it.

Why Bentota

Bentota is on the west coast south of Colombo, at the point where the Bentara Ganga turns and runs parallel to the sea behind a long spit of sand before it finds its mouth. It matters less for the beach than for what accumulated here. This stretch of coast became the island's Ayurvedic corridor, built on long European winter stays, and what that left behind is a concentration of properties where a doctor is genuinely in residence and the kitchen answers to the doctor rather than to a menu. That is the only thing worth selecting for, and it is not visible from a website.

The sea is present and is not the point. Anyone who wants the ocean itself to be the programme belongs on the south coast instead, where the water is the reason to be there. Bentota's usefulness is that it is close enough to Colombo to be reached without losing a day at either end, which matters more than it sounds when the first days are the hardest ones, and quiet enough that the stay is not competing with anything happening outside the gate.

When to come

The west coast is at its brightest outside the south-west monsoon, and that is when the sea is calm and the light is at its best. But the treatment is indoor work and the houses run all year. In the wet months the rain tends to arrive in bursts rather than as a permanent grey, often in the late afternoon when the plan has you resting in any case, and the pavilions are quieter for it. There is an argument, which the doctors will make to you better than we can, that the season matters far less to the programme than it does to the beach. Ask us what the houses are charging for the dates you are considering, and weigh that against how much you mind rain on a roof.

Who it suits, and who it does not

It works for the specific and unglamorous things. Sleep that has stopped working. Digestion that has stopped working. The flat exhaustion that follows a long illness or a long year. Chronic tension that ordinary massage reaches and then does not hold. It works far less well as one component of a busy itinerary, because the effect depends on the week being uninterrupted, and a day trip to Galle in the middle of it undoes more than it adds.

It is also not medicine, and a good doctor will be the first to say so. Ayurveda here is complementary. It does not replace treatment for a diagnosed condition, and a property that suggests otherwise is the wrong property. Tell the doctor what you take and what you have been told, in the first consultation rather than on the fourth day, and expect the plan to be adjusted around it rather than in spite of it.

What to bring

Clothes you do not mind ruining, because the oil does not come out of anything. Loose cotton, long sleeves for the evening, something you can move in. A book you have been meaning to read for years and have never had the empty afternoons for. Do not bring a plan for filling the gaps; there are no gaps. Most people find the phone is the difficult part, and most houses will quietly encourage you to leave it in the room.

Leaving on the eighth morning is a small grief. You step into the car at the right hour, you wave to the gardener, you turn onto the coast road, and you understand that the week has changed something you will not be able to name for some weeks more.

We send people to Bentota when other places have not worked. It is, very often, the room they did not know they had been looking for.