A crypto order book never shuts. That fact leads people to assume the market is one continuous thing. It is closer to a series of markets that share a price, some busy and some nearly empty, depending on which part of the world is awake.
Liquidity keeps hours
Depth is supplied by firms and traders, and they have working days. When the large financial centers are open, more participants are quoting and more orders are arriving. In the gaps between those sessions, and through much of the weekend, fewer are present. The book is still there. It is thinner, and the gap between bid and ask is usually wider.
This is routine and it happens every day. It is a different thing from the stress widening described in spreads widen exactly when you need them tight, which comes from uncertainty. The quiet-hour version comes from absence.
Two costs move together
A quiet hour raises cost in two ways. The spread is wider, so crossing it costs more even for a small order. And there is less size resting at each price, so an order of any weight reaches further into the book and moves the price as it fills. A trade that was routine at a busy hour can be a noticeable event at a quiet one.
It matters most for market orders and stops
A limit order waits at its price, so the quiet hour mostly costs it time. A market order takes whatever is there. A stop is a market order waiting to happen, which is why stops that trigger in thin hours often fill well away from their level. Where to put a stop when liquidity is thin covers that case.
A displayed quote can mislead
At a quiet hour the midpoint between bid and ask is less trustworthy as a price. When the two sides are far apart, the middle is a point nobody is offering to trade at. A chart built from midpoints can show a calm line while the real cost of trading is high. Looking at the spread itself, before trusting the price, is the check.
What follows
The cost of a round trip is not one number per coin. It is a number per coin per hour. An entry made at a busy hour and an exit forced at a quiet one cost more in total than the entry suggested. That asymmetry is common, because entries are chosen and exits often are not.
Knowing the pattern does not require avoiding quiet hours. It requires counting them. A trader who knows the book is thin sizes for it, uses a limit where a limit will do, and does not read a quiet-hour print as if a full market had made it. The weekend nobody closes for covers the largest quiet period of the week.