diff -up comm-beta/calendar/base/src/calAlarmService.js.alarm comm-beta/calendar/base/src/calAlarmService.js
--- comm-beta/calendar/base/src/calAlarmService.js.alarm	2013-09-10 22:58:42.000000000 +0200
+++ comm-beta/calendar/base/src/calAlarmService.js	2013-09-20 09:13:58.753463348 +0200
@@ -64,6 +64,38 @@ function calAlarmService() {
         }
     };
 
+    this.mSleepMonitor = {
+        service: this,
+        interval: 60000,
+        timer: null,
+        expected: null,
+
+        checkExpected: function sm_checkExpected() {
+            let now = Date.now();
+            if (now - this.expected > 1000) {
+                cal.LOG("[calAlarmService] Sleep cycle detected, reloading alarms");
+                this.service.shutdown();
+                this.service.startup();
+            } else {
+                this.expected = now + this.interval;
+            }
+        },
+
+        start: function sm_start() {
+            this.stop();
+            this.expected = Date.now() + this.interval;
+            this.timer = newTimerWithCallback(this.checkExpected.bind(this),
+                                              this.interval, true);
+        },
+
+        stop: function sm_stop() {
+            if (this.timer) {
+                this.timer.cancel();
+                this.timer = null;
+            }
+        }
+    };
+
     this.calendarObserver = {
         alarmService: this,
 
@@ -298,6 +330,8 @@ calAlarmService.prototype = {
             this.mSleepMonitor.start();
         }
 
+        this.mSleepMonitor.start();
+
         this.mStarted = true;
     },
 
@@ -332,6 +366,8 @@ calAlarmService.prototype = {
 
         this.mSleepMonitor.stop();
 
+        this.mSleepMonitor.stop();
+
         this.mStarted = false;
     },