diff --git a/integrations/mqtt_bridge/README.md b/integrations/mqtt_bridge/README.md
index 29d31b04..dae255d4 100644
--- a/integrations/mqtt_bridge/README.md
+++ b/integrations/mqtt_bridge/README.md
@@ -114,5 +114,9 @@ python3 integrations/mqtt_bridge/ledmatrix_mqtt_bridge.py --config integrations/
   discovery itself. Discovery is lazy and normally happens because somebody
   opened the dashboard; without that endpoint a bridge that never does would
   see an empty list.
-- Brightness writes `display.hardware.brightness` through `/api/v3/config/main`.
-  The display service picks it up on its next restart, not instantly.
+- Brightness writes `display.hardware.brightness` by posting
+  `{"brightness": N}` to `/api/v3/config/main`. A JSON save changes only the
+  keys it sends, so the other display settings are left as they were. The
+  display service's config hot reload notices the change within a few seconds
+  and applies it without a restart (while a dim schedule is dimming the panel,
+  the dim level wins until the dim period ends).