Instruments like index futures and forex trade nearly around the clock, but participation is wildly uneven. Session breaks divide the chart so you can see where the New York cash open, the london-session or the overnight range begins and ends.
This matters because levels formed in thin overnight trade behave differently from levels formed on heavy daytime volume. The overnight-high-low frequently acts as a target early in the day precisely because it was set by fewer participants and is easier to run.
Enable session separators and session-anchored tools such as session-vwap and the opening-range. A chart with no session structure treats 3am and 10am as equally meaningful, which they are not.
Related: opening-range, london-session