diff --git a/webroot/rsrc/js/core/behavior-refresh-csrf.js b/webroot/rsrc/js/core/behavior-refresh-csrf.js
index 27c7a9d8ee..b21d2804f3 100644
--- a/webroot/rsrc/js/core/behavior-refresh-csrf.js
+++ b/webroot/rsrc/js/core/behavior-refresh-csrf.js
@@ -48,6 +48,28 @@ JX.behavior('refresh-csrf', function(config) {
   // Refresh the CSRF tokens every 55 minutes.
   setInterval(refresh_csrf, 1000 * 60 * 55);
 
+
+  // If the user walks away from their machine for a long time and it goes to
+  // sleep, we may end up in a situation where many hours have elapsed but
+  // the main refresh callback hasn't been invoked. Once a second, check if
+  // we lost some time and refresh immediately if we did.
+  var last_update = null;
+  var detect_sleep = function() {
+    var now = new Date().getTime();
+    if (last_update) {
+      // If it has been more than a minute since the last update, we lost
+      // some time, probably because the machine went to sleep. Fire the
+      // CSRF update event immediately.
+      var delta = (now - last_update);
+      if (delta > (1000 * 60)) {
+        refresh_csrf();
+      }
+    }
+    last_update = now;
+  };
+  setInterval(every_second, 1000);
+
+
   // Additionally, add the CSRF token as an HTTP header to every AJAX request.
   JX.Request.listen('open', function(r) {
     var via = JX.$U(window.location).getRelativeURI();