Ask anyone who keeps night hours where the night turns and they will say four. Not midnight, which is only a number, and not two, which is simply late. Four is where one thing stops and another starts, and the interesting part is how little of that turn has anything to do with the clock on the wall.
The list of things that do not change
Start here, because it is short and it settles most of the questions that arrive at this hour. The fee does not change: an hour is EUR 180 at four in the morning exactly as it is at four in the afternoon, and there is no night rate anywhere in this arrangement. The arrival window does not change: forty to sixty minutes from confirmation to the door, in every central neighbourhood. The deposit rule does not change. The way a booking is written, agreed and confirmed does not change. Four in the morning is not a special case of anything.
The list of things that do
Three, and they are all on your side of the door.
The first is your temperature. Core temperature bottoms out in the small hours and the trough sits close to this part of the night. A room that felt comfortable at midnight is cold at four, and a body on a table with oil on it loses heat faster than a body under a duvet. Turning the heating up before she arrives is not fussiness at this hour; it is the difference between a session that works and one spent quietly tensing against the room.
The second is your judgement about length. At four, tiredness and alertness sit on top of each other in a way that is genuinely hard to read from inside. Guests routinely over-order or under-order here, and both are uncomfortable. The safer instinct is the longer one: two hours ending at six is a coherent end to a night, while an hour ending at five leaves you awake in a strange fragment with nothing to do in it.
The third is the roster. This is the narrowest part of the night for choice. Fewer therapists keep four than keep two, and far fewer than keep eleven in the evening. Flexibility about who comes is worth much more than flexibility about when at this hour, and a message that says so directly gets a faster answer than one that names a single person and waits.
The two guests who arrive here
Four collects two entirely different people and they need opposite advice.
The first has not been to bed. They are at the end of a long evening, the city has emptied, and the booking is the last thing in a sequence rather than the first thing in one. This guest should book something that finishes the night: slow, long, with no expectation of being upright afterwards. A shower, the curtains closed properly, and sleep.
The second has been to bed and is wide awake because their body is keeping time somewhere else entirely. This guest is at the start of a day, not the end of a night, and the right booking is different: still unhurried, but timed so that it ends with the light rather than before it, which sets a body up to stay awake through a real morning. The guide to four until seven takes both cases apart properly.
Buildings at four
This is the emptiest a city building gets. Not the most locked, which is usually around one, but the emptiest. Night staff, where there are any, are at the low point of their own shift. Lifts are free. Corridors are silent in a way that makes ordinary noise sound enormous, which is worth knowing when you open a door.
What it means practically is that entry details matter more here than at any other hour. A street door on a code, a lift that wants a keycard, a night entrance around the side: any of those unmentioned at four means someone standing on a pavement in the coldest part of the night. Put it in the first message. The night entry note lists the four cases.
A last practical thing
Eat something small if it has been a long time. Not a meal, and not at the last minute, but a body running on nothing since eight in the evening does not respond well to two hours of work at four in the morning. Water, something plain, the heating up, a lamp instead of the ceiling. Then write, with the hour, the length, the area and the entrance in the same message, and let the thread do the rest.