diff --git a/js/views/app_view.js b/js/views/app_view.js
index f271b2149..144cb3e2c 100644
--- a/js/views/app_view.js
+++ b/js/views/app_view.js
@@ -22,7 +22,7 @@
       openInbox: 'openInbox',
     },
     applyTheme() {
-      const theme = storage.get('theme-setting') || 'dark';
+      const theme = storage.get('theme-setting') || 'light';
       this.$el
         .removeClass('light-theme')
         .removeClass('dark-theme')
diff --git a/ts/components/session/ActionsPanel.tsx b/ts/components/session/ActionsPanel.tsx
index 661c1b345..6c4580254 100644
--- a/ts/components/session/ActionsPanel.tsx
+++ b/ts/components/session/ActionsPanel.tsx
@@ -57,10 +57,45 @@ export class ActionsPanel extends React.Component<Props, State> {
           },
           'refreshAvatarCallback'
         );
+
+        void this.showLightThemeDialogIfNeeded();
       }
     );
   }
 
+  public async showLightThemeDialogIfNeeded() {
+    const currentTheme = window.Events.getThemeSetting(); // defaults to light on new registration
+    if (currentTheme !== 'light') {
+      const message = 'Light Mode';
+      const messageSub =
+        'Feeling the dark side more? Just toggle the theme from the bottom-left moon icon.';
+      const hasSeenLightMode = await getItemById('hasSeenLightModeDialog');
+
+      if (hasSeenLightMode?.value === true) {
+        // if hasSeen is set and true, we have nothing to do
+        return;
+      }
+      // force light them right now, then ask for permission
+      await window.Events.setThemeSetting('light');
+      // FIXME add the SUN icon
+      window.confirmationDialog({
+        message,
+        messageSub,
+        resolve: async () => {
+          const data = {
+            id: 'hasSeenLightModeDialog',
+            value: true,
+          };
+          void createOrUpdateItem(data);
+        },
+        okTheme: 'default primary',
+        hideCancel: true,
+        sessionIcon: SessionIconType.Sun,
+        iconSize: SessionIconSize.Max,
+      });
+    }
+  }
+
   public refreshAvatarCallback(conversation: any) {
     if (conversation.changed?.profileAvatar) {
       this.setState({
diff --git a/ts/components/session/RegistrationTabs.tsx b/ts/components/session/RegistrationTabs.tsx
index 6faec374e..91c9cd3ce 100644
--- a/ts/components/session/RegistrationTabs.tsx
+++ b/ts/components/session/RegistrationTabs.tsx
@@ -12,6 +12,7 @@ import { SessionHtmlRenderer } from './SessionHTMLRenderer';
 import { SessionIdEditable } from './SessionIdEditable';
 import { SessionSpinner } from './SessionSpinner';
 import { StringUtils, ToastUtils } from '../../session/utils';
+import { createOrUpdateItem } from '../../../js/modules/data';
 
 enum SignInMode {
   Default,
@@ -862,6 +863,12 @@ export class RegistrationTabs extends React.Component<{}, State> {
         language,
         trimName
       );
+      // FIXME remove everything related to hasSeenLightModeDialog at some point in the future (27/08/2020)
+      const data = {
+        id: 'hasSeenLightModeDialog',
+        value: true,
+      };
+      await createOrUpdateItem(data);
       trigger('openInbox');
     } catch (e) {
       ToastUtils.push({