diff --git a/src/main/java/com/bugsnag/Bugsnag.java b/src/main/java/com/bugsnag/Bugsnag.java
index <HASH>..<HASH> 100644
--- a/src/main/java/com/bugsnag/Bugsnag.java
+++ b/src/main/java/com/bugsnag/Bugsnag.java
@@ -472,6 +472,10 @@ public class Bugsnag {
     /**
      * Manually starts tracking a new session.
      *
+     * Note: sessions are currently tracked on a per-thread basis. Therefore, if this method were called
+     * from Thread A then Thread B, two sessions would be considered 'active'. Any custom strategy used
+     * to track sessions should take this into account.
+     *
      * Automatic session tracking can be enabled via
      * {@link Bugsnag#setAutoCaptureSessions(boolean)}, which will automatically create a new
      * session for each request
docs: document that sessions are tracked on a per-thread basis