The oldest instruction in Ayurveda is not about what to take. It is about when.
Before the tradition arrives at any remedy it sets out a day. Dinacharya, from dina, day, and charya, conduct, is the daily regimen: what is done, and at which hour, from waking to sleeping. Vagbhata gives it the second chapter of the Ashtanga Hridaya, immediately after the opening. Charaka handles the same material in the fifth chapter of the Sutrasthana. In both, regimen comes before pharmacy.
That ordering is the whole argument. A physician who has to reach for a remedy has already lost some ground. The regimen exists so that the reaching is needed less often.
A day divided
The classical division is simple and easy to hold in the head. The twenty-four hours are read as six blocks of roughly four, each attributed to one of the three doshas, and each block repeats once by day and once by night.
Morning from about six to ten is kapha: heavy, cool, slow to start. Midday to mid-afternoon is pitta: hot, sharp, the hours of appetite and work. Late afternoon into evening is vata: mobile, dry, quick and easily scattered. Then the same three again through the night, which places kapha over the early evening and gives the close of the day its heaviness.
The tradition did not ask what you were doing. It asked at what hour you were doing it.
Whether one accepts the underlying physiology or not, the observation behind it is not eccentric. A body is not the same instrument at six in the morning as at ten at night, and a great deal of ordinary difficulty comes from asking it to be.
Where modern work agrees
Chronobiology arrived at something adjacent by a different route. The 2017 Nobel Prize in Physiology or Medicine went to Jeffrey Hall, Michael Rosbash and Michael Young for their work on the molecular machinery of the circadian clock, the set of genes and proteins by which cells keep approximate time. Almost every tissue in the body carries one.
The overlap is not a vindication of Ayurveda and should not be sold as one. The two systems describe different things in incompatible language. What they share is a premise: that timing is not a detail laid over physiology but part of it.
The evening portion
Most of what is written about dinacharya concerns the morning, which is where the elaborate parts sit. The evening is treated more briefly and more plainly. Eat earlier and lighter. Let the light go down. Do not carry the day's arguments into the last hour. Sleep at a consistent time.
None of that is difficult to understand. It is only difficult to do, and it is difficult to do because nothing in a modern evening is arranged to help. The hours after eight belong to whatever is brightest and loudest in the room.
What we take from it
ZANAR is not prescribing a regimen and Nidravati Vidhana is not an Ayurvedic medicine. What the House takes from dinacharya is narrower and, we think, more useful: the idea that one hour, kept in the same shape most nights, is worth more than an occasional grand effort.
The ritual is seven to ten minutes long because that is a length a person will still be keeping in March. It sits at the close of the evening because that is the hour the tradition, and the body, both mark as the descent.
The rest of the day is yours. The tradition only ever claimed that the hours are not interchangeable.
Nidravati Vidhana is an aromatherapy preparation for the inhalation of vapour only. It is not a medicine, and no part of it is to be ingested.