diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 3664fae..88e7ccb 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -5,6 +5,7 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission android:name="android.permission.WAKE_LOCK"/>
 
     <application
         android:name=".MyApplication"
diff --git a/app/src/main/java/com/ray650128/iosclockwidget/ClockUpdateService.kt b/app/src/main/java/com/ray650128/iosclockwidget/ClockUpdateService.kt
index df2e2da..df9dc78 100644
--- a/app/src/main/java/com/ray650128/iosclockwidget/ClockUpdateService.kt
+++ b/app/src/main/java/com/ray650128/iosclockwidget/ClockUpdateService.kt
@@ -2,9 +2,13 @@ package com.ray650128.iosclockwidget
 
 import android.annotation.SuppressLint
 import android.app.*
+import android.content.BroadcastReceiver
+import android.content.Context
 import android.content.Intent
+import android.content.IntentFilter
 import android.os.Build
 import android.os.IBinder
+import android.util.Log
 import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationManagerCompat
 import com.ray650128.iosclockwidget.receiver.IOSClockWidget
@@ -16,16 +20,38 @@ class ClockUpdateService : Service() {
     private val timerThread = Thread {
         while (true) {
             if (!isServiceRunning) break
-            val calendar = Calendar.getInstance()
-            val second = calendar[Calendar.SECOND]
-            val millisecond = calendar[Calendar.MILLISECOND]
-            // 計算時、分、秒的旋轉角度
-            secondAngle = ((second + (millisecond / 1000f)) * 360f / 60f)//(second * 360f / 60f)
-            sendWidgetIntent()
-            Thread.sleep(100)
+            if (isScreenOn) {
+                val calendar = Calendar.getInstance()
+                val second = calendar[Calendar.SECOND]
+                val millisecond = calendar[Calendar.MILLISECOND]
+                // 計算時、分、秒的旋轉角度
+                secondAngle = ((second + (millisecond / 1000f)) * 360f / 60f)//(second * 360f / 60f)
+                sendWidgetIntent()
+                Thread.sleep(100)
+            }
         }
     }
 
+    private val screenOnOffReceiver = object : BroadcastReceiver() {
+        override fun onReceive(context: Context?, intent: Intent?) {
+            val action = intent?.action ?: return
+            when (action) {
+                Intent.ACTION_SCREEN_OFF -> isScreenOn = false
+                Intent.ACTION_SCREEN_ON -> isScreenOn = true
+            }
+        }
+    }
+
+    private val screenOnOffIntentFilter: IntentFilter by lazy {
+        IntentFilter().apply {
+            this.addCategory(Intent.CATEGORY_DEFAULT)
+            this.addAction(Intent.ACTION_SCREEN_ON)
+            this.addAction(Intent.ACTION_SCREEN_OFF)
+        }
+    }
+
+    private var isScreenOn = true
+
     override fun onBind(intent: Intent): IBinder {
         throw UnsupportedOperationException("Not yet implemented")
     }
@@ -36,6 +62,9 @@ class ClockUpdateService : Service() {
         isServiceRunning = true
 
         startForeground()
+
+        registerReceiver(screenOnOffReceiver, screenOnOffIntentFilter)
+        Log.i(TAG, "Service on, register Broadcast Receiver.")
     }
 
     @SuppressLint("WakelockTimeout")
@@ -47,7 +76,9 @@ class ClockUpdateService : Service() {
 
     override fun onDestroy() {
         super.onDestroy()
+        unregisterReceiver(screenOnOffReceiver)
         isServiceRunning = false
+        Log.i(TAG, "Service off, Unregister Broadcast Receiver and stop self.")
     }
 
     //region Foreground Service 必要通知
diff --git a/app/src/main/java/com/ray650128/iosclockwidget/receiver/AutoStartReceiver.kt b/app/src/main/java/com/ray650128/iosclockwidget/receiver/AutoStartReceiver.kt
index db2d85a..c279db0 100644
--- a/app/src/main/java/com/ray650128/iosclockwidget/receiver/AutoStartReceiver.kt
+++ b/app/src/main/java/com/ray650128/iosclockwidget/receiver/AutoStartReceiver.kt
@@ -10,11 +10,15 @@ import com.ray650128.iosclockwidget.utils.PreferenceUtil
 class AutoStartReceiver : BroadcastReceiver() {
 
     override fun onReceive(context: Context?, intent: Intent?) {
-        Log.d("AutoStartReceiver", "intent: ${intent?.action}")
+        Log.d(TAG, "intent: ${intent?.action}")
         if (context == null || intent == null) return
         if (!PreferenceUtil.isGranted) return
         val i = Intent(context, ClockUpdateService::class.java)
         context.startForegroundService(i)
-        Log.d("AutoStartReceiver", "Boot completed.")
+        Log.d(TAG, "Boot completed.")
+    }
+
+    companion object {
+        private val TAG = AutoStartReceiver::class.java.simpleName
     }
 }
\ No newline at end of file