diff --git a/app/src/main/java/org/secuso/aktivpause/activities/SplashActivity.java b/app/src/main/java/org/secuso/aktivpause/activities/SplashActivity.java
index e320223..98b7f20 100644
--- a/app/src/main/java/org/secuso/aktivpause/activities/SplashActivity.java
+++ b/app/src/main/java/org/secuso/aktivpause/activities/SplashActivity.java
@@ -22,6 +22,7 @@ public class SplashActivity extends AppCompatActivity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
+        setDayNightTheme(PreferenceManager.getDefaultSharedPreferences(this).getInt("theme", AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM));
         super.onCreate(savedInstanceState);
 
         Intent mainIntent = null;
@@ -40,4 +41,17 @@ public class SplashActivity extends AppCompatActivity {
         SplashActivity.this.finish();
     }
 
+    private void setDayNightTheme(int theme) {
+        switch (theme) {
+            case AppCompatDelegate.MODE_NIGHT_NO:
+                setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
+                break;
+            case AppCompatDelegate.MODE_NIGHT_YES:
+                setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
+                break;
+            default:
+                setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM);
+        }
+    }
+
 }
diff --git a/app/src/main/java/org/secuso/aktivpause/activities/helper/BaseActivity.java b/app/src/main/java/org/secuso/aktivpause/activities/helper/BaseActivity.java
index 23e59c2..237d877 100644
--- a/app/src/main/java/org/secuso/aktivpause/activities/helper/BaseActivity.java
+++ b/app/src/main/java/org/secuso/aktivpause/activities/helper/BaseActivity.java
@@ -27,7 +27,9 @@ import org.secuso.aktivpause.activities.SettingsActivity;
 import org.secuso.aktivpause.activities.TimerActivity;
 import org.secuso.aktivpause.activities.tutorial.TutorialActivity;
 
+
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static androidx.appcompat.app.AppCompatDelegate.setDefaultNightMode;
 
 /**
  *
@@ -168,6 +170,29 @@ public abstract class BaseActivity extends AppCompatActivity implements OnNaviga
                 //intent.putExtra( PreferenceActivity.EXTRA_NO_HEADERS, true );
                 createBackStack(intent);
                 break;
+            case R.id.nav_theme:
+                new AlertDialog.Builder(this)
+                .setTitle(R.string.title_theme)
+                .setPositiveButton(R.string.follow_system, (dialog, which) -> {
+                    mSharedPreferences.edit().putInt("theme",AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM).apply();
+                    setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM);
+                    Intent thisIntent = new Intent(this, getClass());
+                    createBackStack(thisIntent);
+                })
+                .setNegativeButton(R.string.dark, (dialog, which) -> {
+                    mSharedPreferences.edit().putInt("theme",AppCompatDelegate.MODE_NIGHT_YES).apply();
+                    setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
+                    Intent thisIntent = new Intent(this, getClass());
+                    createBackStack(thisIntent);
+                })
+                .setNeutralButton(R.string.light, (dialog, which) -> {
+                    mSharedPreferences.edit().putInt("theme",AppCompatDelegate.MODE_NIGHT_NO).apply();
+                    setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
+                    Intent thisIntent = new Intent(this, getClass());
+                    createBackStack(thisIntent);
+                })
+                .show();
+                break;
             default:
         }
         overridePendingTransition(0,0);
diff --git a/app/src/main/res/menu/nav_drawer.xml b/app/src/main/res/menu/nav_drawer.xml
index 9711168..3d92a94 100644
--- a/app/src/main/res/menu/nav_drawer.xml
+++ b/app/src/main/res/menu/nav_drawer.xml
@@ -22,6 +22,10 @@
             android:id="@+id/nav_settings"
             android:icon="@drawable/ic_settings_24"
             android:title="@string/title_activity_settings" />
+        <item
+            android:id="@+id/nav_theme"
+            android:icon="@drawable/ic_theme_24"
+            android:title="@string/title_theme" />
         <item
             android:id="@+id/nav_help"
             android:icon="@drawable/ic_help"
diff --git a/app/src/main/res/values-de/strings.xml b/app/src/main/res/values-de/strings.xml
index 1f79287..ab78882 100644
--- a/app/src/main/res/values-de/strings.xml
+++ b/app/src/main/res/values-de/strings.xml
@@ -176,5 +176,9 @@
     <string name="dialog_evaluation_title">Online-Befragung</string>
     <string name="dialog_evaluation_yes">Ja</string>
     <string name="menu_display_evaluation_dialog">Online-Befragung</string>
+    <string name="title_theme">Theme</string>
+    <string name="follow_system">Standard</string>
+    <string name="dark">Dunkel</string>
+    <string name="light">Hell</string>
 
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 8c4bb58..f763d4a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -59,6 +59,10 @@
     <string name="set_contains_no_exercises">This set contains no exercises.</string>
     <string name="take_a_break_now">Take a break now! Click here to do your chosen exercises.</string>
     <string name="title_activity_settings">Settings</string>
+    <string name="title_theme">Theme</string>
+    <string name="follow_system">Standard</string>
+    <string name="dark">Dark Theme</string>
+    <string name="light">Light Theme</string>
     <string name="no_exercise_sets">No exercise sets available. Please create a new one.</string>
     <string name="activity_title_manage_exercise_sets">Exercise Sets</string>
     <string name="activity_title_edit_exercise_set">Edit Exercise Set</string>