diff --git a/components/sensor/index.rst b/components/sensor/index.rst
index 595e3c54d..3ac3be459 100644
--- a/components/sensor/index.rst
+++ b/components/sensor/index.rst
@@ -389,7 +389,10 @@ In comparison to the ``throttle`` filter it won't discard any values. In compari
 ``heartbeat``
 *************
 
-Send the last value that this sensor in the specified time interval.
+Send the value periodically with the specified time interval.
+If the sensor value changes during the interval the interval will not reset.
+The last value of the sensor will be sent.
+
 So a value of ``10s`` will cause the filter to output values every 10s regardless
 of the input values.