diff --git a/oled.ino b/oled.ino
index b3b44ac..f9afbf1 100644
--- a/oled.ino
+++ b/oled.ino
@@ -4,25 +4,52 @@
 
 #define BTN_PORT 7
 #define DHT_PORT 8
+#define PHOTO_RESISTOR A0
 
-#define CAROUSEL_LENGTH 2
+#define READ_INTERVAL 4000
+#define CAROUSEL_INTERVAL 2000
+
+#define CAROUSEL_LENGTH 3
 
 DHT dht(DHT_PORT, DHT11);
 GyverOLED<SSD1306_128x64, OLED_BUFFER> oled;
 OneButton button(BTN_PORT, true, true);
 
+const unsigned char bmp_moon [] PROGMEM = {
+  0x00, 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfc, 0xfe, 0xfe, 0xff, 0x01, 0x00, 0x00, 0x00, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0xf0, 0xfe, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfc, 0xf0, 0xc0, 0x80, 
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 
+  0x0f, 0x7f, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 
+  0xff, 0xfe, 0xfc, 0xfc, 0xf8, 0xf8, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0xf0, 0x70, 0x18, 
+  0x00, 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x3f, 0x7f, 0x7f, 0x7f, 0xff, 0xff, 0xff, 0xff, 
+  0xff, 0xff, 0xff, 0xff, 0x7f, 0x7f, 0x7f, 0x3f, 0x3f, 0x1f, 0x0f, 0x0f, 0x03, 0x01, 0x00, 0x00
+  };
+
+  const unsigned char bmp_sun [] PROGMEM = {
+  0x00, 0x00, 0x00, 0x00, 0x20, 0x70, 0xe0, 0xc0, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1f, 
+  0x1f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0xc0, 0xe0, 0x70, 0x20, 0x00, 0x00, 0x00, 0x00, 
+  0x80, 0x80, 0x80, 0x80, 0x80, 0x00, 0x00, 0x01, 0xe0, 0xf8, 0xfc, 0x1e, 0x0e, 0x07, 0x07, 0x07, 
+  0x07, 0x07, 0x07, 0x0e, 0x1e, 0xfc, 0xf8, 0xe0, 0x01, 0x00, 0x00, 0x80, 0x80, 0x80, 0x80, 0x80, 
+  0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x80, 0x07, 0x1f, 0x3f, 0x78, 0x70, 0xe0, 0xe0, 0xe0, 
+  0xe0, 0xe0, 0xe0, 0x70, 0x78, 0x3f, 0x1f, 0x07, 0x80, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x0e, 0x07, 0x03, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf8, 
+  0xf8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03, 0x07, 0x0e, 0x04, 0x00, 0x00, 0x00, 0x00
+};
+
 float h = -1;
 float c = -1;
 float f = -1;
+float l = -1;
 
 unsigned long timer_read = 0;
-unsigned long timer_print = 0;
+unsigned long timer_carousel = 0;
 
-int prev = CAROUSEL_LENGTH;
+byte prev = CAROUSEL_LENGTH;
 bool show_carousel = true;
 bool temp_far = false;
 
-void with_header(String title, void (*cb)()) {
+void with_header(const String& title, void (*cb)()) {
    oled.rect(0, 0, 128, 11, 1);
    
    oled.setCursorXY(2, 2);
@@ -31,11 +58,12 @@ void with_header(String title, void (*cb)()) {
    oled.print(title);
    oled.textMode(BUF_REPLACE);
 
-   oled.setCursorXY(0, 20);
+   oled.setCursorXY(2, 20);
    cb();
 }
 
 void with_scaleup(int factor, void (*cb)()) {
+  oled.setCursorXY(2, 29);
   oled.setScale(factor);
   cb();
   oled.setScale(1);
@@ -50,7 +78,8 @@ void print_hum() {
   
   oled.roundRect(107, 20, 127, 63, 1);
   oled.roundRect(109, 22, 125, 61, 0);
-  oled.roundRect(110, 60 - (60 - 23)*(h / 100), 124, 60, 1);
+  if (h > 0)
+    oled.roundRect(110, 60 - (60 - 23)*(h / 100), 124, 60, 1);
 }
 
 void print_temp() {
@@ -60,31 +89,49 @@ void print_temp() {
     oled.print(fallback(c, 1) + "C");
 }
 
+void print_light() {
+  bool is_night = l > 450;
+
+  String str = F("It's ");
+  if (is_night)
+    str += F("night");
+  else
+    str += F("day");
+
+  oled.setCursorXY((127 - str.length()*6)/2, 55);
+  oled.println(str);
+  
+  oled.drawBitmap(48, 17, is_night ? bmp_moon : bmp_sun, 32, 32, BITMAP_NORMAL, BUF_ADD);
+}
+
 void print_settings() {
   oled.invertText(temp_far);
-  oled.print("Fahrenheit");
+  oled.print(F("Fahrenheit"));
   oled.invertText(false);
       
   oled.print("/");
       
   oled.invertText(!temp_far);
-  oled.print("Celsius");
+  oled.print(F("Celsius"));
   oled.invertText(false);
 }
 
-void display(int screen) {
+void display(byte screen) {
   oled.clear();
   oled.home();
   
   switch(screen) {
     case 0:
-      with_header("Humidity", []() { with_scaleup(3, &print_hum); });
+      with_header(F("Humidity"), []() { with_scaleup(3, &print_hum); });
       break;
     case 1:
-      with_header("Temperature", []() { with_scaleup(3, &print_temp); });
+      with_header(F("Temperature"), []() { with_scaleup(3, &print_temp); });
+      break;
+    case 2:
+      with_header(F("Lightness"), &print_light);
       break;
     case CAROUSEL_LENGTH:
-      with_header("Settings", &print_settings);
+      with_header(F("Settings"), &print_settings);
       break;
   }
   
@@ -92,9 +139,8 @@ void display(int screen) {
 }
 
 void show_next() {
-  timer_print = millis();
+  timer_carousel = millis();
   prev = (prev + 1) % CAROUSEL_LENGTH;
-  Serial.println("Next is " + String(prev));
   display(prev);
 }
 
@@ -109,6 +155,8 @@ void read_data() {
   h = dht.readHumidity();
   c = dht.readTemperature();
   f = dht.readTemperature(true);
+
+  l = analogRead(PHOTO_RESISTOR);
 }
 
 void handle_click() {
@@ -146,7 +194,7 @@ void setup() {
   button.attachLongPressStart(&handle_lpress);
   
   timer_read = millis();
-  timer_print = millis();
+  timer_carousel = millis();
 
   display(0);
 }
@@ -156,6 +204,6 @@ void loop() {
   
   oled.clear();
   
-  every(4000, timer_read, &read_data);
-  every(2000, timer_print, []() { if (show_carousel) show_next(); });
+  every(READ_INTERVAL, timer_read, &read_data);
+  every(CAROUSEL_INTERVAL, timer_carousel, []() { if (show_carousel) show_next(); });
 }