There is a category of booking that people arrange without noticing what they have arranged. It starts at four or five in the morning and it finishes after the light has arrived. On paper it is a late night booking. In practice it belongs half to one day and half to the next, and the crossing changes several things that are worth thinking about in advance.
Where the line actually falls
Not at a fixed hour, which is the first thing to get right. In late June the light here starts before five. In December it does not arrive until well past eight. The same booking at half past five is a night booking in winter and a morning one in summer, and your body will treat it accordingly regardless of what the clock says.
So the practical question is not what time it is but how much dark is left. A two hour session starting at four in June ends in full daylight. The same session starting at four in November ends with the night still going.
What the crossing does to sleep
This is the part that catches people out. A session that ends in daylight makes sleeping afterwards significantly harder, because light is the strongest single input to the system that decides when you are awake. Finishing at seven in June and expecting to sleep until noon is a plan that needs help: curtains closed properly before the session rather than after, and a room that is genuinely dark rather than mostly dark.
The alternative is to stop fighting it and treat the booking as the start of a day rather than the end of a night. That works well for a guest whose morning has nothing immovable in it. It works badly for a guest with a checkout or a meeting, which is a scheduling decision rather than anything to do with the session.
What to order across the line
Longer, and slower. A one hour booking that starts at five and ends at six lands in the worst possible place: after the night has finished and before the morning has started, with nothing on either side of it. Two hours that start at five and end at seven arrive somewhere. Three hours that start at four and end at seven arrive somewhere better.
The overnight is the format that handles the crossing most comfortably, precisely because it is not a session but a block: eight hours holds the dark, the light, sleep, a shower and hands that come back later, which is a more honest description of what this part of the night actually wants. The guide to the eight hour block sets out how it works.
The roster across the line
This is the narrowest stretch of the whole night for choice. Fewer therapists keep five in the morning than keep two, and fewer keep two than keep eleven. A booking that crosses the line goes most smoothly when you are flexible about who comes rather than about when, and when it is arranged before the stretch begins rather than inside it.
The arrival window does not move: forty to sixty minutes from a confirmed booking to a knock, in every central neighbourhood, at five in the morning as at five in the evening. Nothing about the fee moves either. There is no night rate and no dawn rate, and a booking that crosses from one day into the next is priced exactly as a booking that does not.
The guest this suits most
Someone whose clock belongs somewhere else. For a body still keeping time several zones away, five in the morning is not the edge of anything; it is an ordinary part of the afternoon, and the crossing into daylight is not a boundary at all. That guest can book long, start late and sleep afterwards without any of the difficulty described above, and the guide for inverted clocks explains why the arithmetic is so different.
One last practical thing
Decide about the morning before you book, not after. If something at nine is immovable, book three hours ending at two and go to sleep. If nothing is, then the booking across the line is one of the better ones available, and the only preparation it needs is a pair of curtains closed properly while you still care enough to do it well.