diff --git a/Source/TODO b/Source/TODO
new file mode 100644
index 0000000..632776c
--- /dev/null
+++ b/Source/TODO
@@ -0,0 +1,13 @@
+- After turning off, turning on doesn't really respond well to the option button
+- Store value in EEPROM (after a timeout)
+- Long press shows menu with reset option (menu prevents accidental resets)
+
+
+
+
+
+Pin-out reminder:
+
+SW2 = -     = pin 2, PB3
+SW3 = menu  = pin 3, PB4
+SW1 = +     = pin 6, PB1
\ No newline at end of file
diff --git a/Source/src/buttons.c b/Source/src/buttons.c
index 3f6637a..a221ce0 100644
--- a/Source/src/buttons.c
+++ b/Source/src/buttons.c
@@ -37,7 +37,6 @@ void buttons_init()
 
   // Enable timer interrupt
   TIMSK = _BV(OCIE0A);
-
   sei();
 }
 
diff --git a/Source/src/main.c b/Source/src/main.c
index 4f3f9ec..5bba500 100644
--- a/Source/src/main.c
+++ b/Source/src/main.c
@@ -17,6 +17,7 @@ int main()
   // Delay is required on power-on for the SSD1306 to initialize,
   _delay_ms(40);
   ssd1306_init();
+  ssd1306_clear();
 
   buttons_init();
 
@@ -28,6 +29,7 @@ int main()
       if (powerState == On)
       {
           handleCurrentScreen();
+          sleepUntilButton(_BV(BUTTON_UP) | _BV(BUTTON_DOWN) | _BV(BUTTON_OPTION));
       }
     }
   }
diff --git a/Source/src/power.c b/Source/src/power.c
index 1ef0a8f..fe62ef2 100644
--- a/Source/src/power.c
+++ b/Source/src/power.c
@@ -1,10 +1,19 @@
 #include "power.h"
 #include <stdint.h>
 #include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
 #include <util/delay.h>
 #include <ssd1306xled.h>
 
 
+// I'm not really keen on referencing the buttons directly from here,
+// feels like a coding red flag. It'll do for now until I come up with
+// a better design. Or forget about it most likely.
+#include "buttons.h"
+
+
+
 
 #define VccOffTreshold 3000
 #define VccOnTreshold 3100
@@ -12,6 +21,7 @@
 #define SSD1306CommandOff 0xAE
 #define SSD1306CommandOn 0xAF
 
+#define SleepInterval8s (_BV(WDP3) | _BV(WDP0))
 
 
 PowerState powerState = BatteryLow;
@@ -41,9 +51,7 @@ void checkPower()
       if (vcc < VccOffTreshold)
       {
         setPowerState(BatteryLow);
-
-        // TODO go into a sleep cycle until the battery is recharged
-        _delay_ms(10);
+        sleepUntilTimer(SleepInterval8s);
       }
 
       break;
@@ -52,16 +60,12 @@ void checkPower()
       if (vcc > VccOnTreshold)
         setPowerState(On);
       else
-      {
-        // TODO continue sleep cycle
-        _delay_ms(10);
-      }
+        sleepUntilTimer(SleepInterval8s);
 
       break;
 
     case ManualOff:
-      // TODO go into sleep mode
-      _delay_ms(10);
+      sleepUntilButton(_BV(BUTTON_OPTION));
       break;
   }
 }
@@ -75,6 +79,7 @@ void setPowerState(PowerState newState)
   {
     case On:
       ssd1306_send_command(SSD1306CommandOn);
+      //buttons_init(); TODO this doesn't help, fix it!
       break;
 
     case BatteryLow:
@@ -144,4 +149,75 @@ uint16_t readVCC() {
   ADCSRA &= ~(_BV(ADEN));
 
   return result == 0 ? 0 : 1125300L / result; // Calculate Vcc (in mV); 1125300 = 1.1*1023*1000
+}
+
+
+inline void sleepStart()
+{
+  // Turn ADC off
+  ADCSRA &= ~_BV(ADEN);
+  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+
+  // Set sleep bit and halt the CPU
+  sleep_enable();
+  sei();
+  sleep_cpu();
+
+  // ...goooood morning!
+  cli();
+}
+
+
+inline void sleepEnd()
+{
+  sleep_disable();
+  ADCSRA |= _BV(ADEN);
+
+  sei();
+}
+
+
+void sleepUntilButton(uint8_t pinMask)
+{
+  // Enable pin change interrupts
+  GIMSK |= _BV(PCIE);
+
+  // Set up pin change mask
+  PCMSK = pinMask;
+
+  sleepStart();
+  PCMSK = 0;
+  sleepEnd();
+}
+
+
+void sleepUntilTimer(uint8_t prescaler)
+{
+  // Disable watchdog reset flag
+  MCUSR &= ~_BV(WDRF);
+
+  // Enable watchdog
+  WDTCR |= _BV(WDCE) | _BV(WDE);
+
+  // Set timeout value and enable interrupt mode
+  WDTCR = prescaler | _BV(WDIE);
+
+  sleepStart();
+
+  // Disable watchdog (need to write a logic one first, see datasheet)
+  WDTCR |= _BV(WDCE) | _BV(WDE);
+  WDTCR = 0;
+
+  sleepEnd();
+}
+
+
+// Interrupt for pin changes
+ISR(PCINT0_vect)
+{
+}
+
+// Interrupt for watchdog timer
+ISR(WDT_vect)
+{
 }
\ No newline at end of file
diff --git a/Source/src/power.h b/Source/src/power.h
index 4fa9815..4ce151f 100644
--- a/Source/src/power.h
+++ b/Source/src/power.h
@@ -13,6 +13,21 @@ extern uint16_t vcc;
 extern void checkPower();
 extern void setPowerState(PowerState newState);
 
+extern void sleepUntilButton(uint8_t pinMask);
+
+// 0 = 16 ms
+// 1 = 32 ms
+// 2 = 64 ms
+// 3 = 128 ms
+// 4 = 250 ms
+// 5 = 500 ms
+// 6 = 1 sec
+// 7 = 2 sec
+// 8 = 4 sec
+// 9 = 8 sec
+extern void sleepUntilTimer(uint8_t interval);
+
+
 extern uint8_t getScreenInvalidated();
 extern void setScreenInvalidated();