diff --git a/common.mk b/common.mk
index f9faf2f9..4054893b 100644
--- a/common.mk
+++ b/common.mk
@@ -47,5 +47,11 @@ ifdef $(or MOUSEKEY_ENABLE, PS2_MOUSE_ENABLE)
     OPT_DEFS += -DMOUSE_ENABLE
 endif
 
+ifdef SLEEP_LED_ENABLE
+    SRC += $(COMMON_DIR)/sleep_led.c
+    OPT_DEFS += -DSLEEP_LED_ENABLE
+endif
+
+
 # Search Path
 VPATH += $(TOP_DIR)/common
diff --git a/common/sleep_led.c b/common/sleep_led.c
new file mode 100644
index 00000000..edf68c35
--- /dev/null
+++ b/common/sleep_led.c
@@ -0,0 +1,84 @@
+#include <stdint.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+#include "led.h"
+#include "sleep_led.h"
+
+/* Software PWM
+ *  ______           ______           __
+ * |  ON  |___OFF___|  ON  |___OFF___|   ....
+ * |<-------------->|<-------------->|<- ....
+ *     PWM period       PWM period
+ *
+ * 256              interrupts/period[resolution]
+ * 64               periods/second[frequency]
+ * 256*64           interrupts/second
+ * F_CPU/(256*64)   clocks/interrupt
+ */
+#define SLEEP_LED_TIMER_TOP F_CPU/(256*64)
+
+void sleep_led_init(void)
+{
+    /* Timer1 setup */
+    /* CTC mode */
+    TCCR1B |= _BV(WGM12);
+    /* Clock selelct: clk/1 */
+    TCCR1B |= _BV(CS10);
+    /* Set TOP value */
+    uint8_t sreg = SREG;
+    cli();
+    OCR1AH = (SLEEP_LED_TIMER_TOP>>8)&0xff;
+    OCR1AL = SLEEP_LED_TIMER_TOP&0xff;
+    SREG = sreg;
+}
+
+void sleep_led_enable(void)
+{
+    /* Enable Compare Match Interrupt */
+    TIMSK1 |= _BV(OCIE1A);
+}
+
+void sleep_led_disable(void)
+{
+    /* Disable Compare Match Interrupt */
+    TIMSK1 &= ~_BV(OCIE1A);
+}
+
+
+/* Breathing Sleep LED brighness(PWM On period) table
+ * (32[steps] * 8[duration]) / 64[PWM periods/s] = 4 second breath cycle
+ */
+static const uint8_t breathing_table[32] PROGMEM = {
+    0, 0, 0, 2, 9, 21, 37, 56, 78, 127, 151, 175, 197, 216, 232, 244,
+    254, 244, 216, 197, 175, 151, 127, 78, 56, 37, 21, 9, 2, 0, 0, 0
+};
+
+ISR(TIMER1_COMPA_vect)
+{
+    /* Software PWM
+     * timer:1111 1111 1111 1111
+     *       \----/\-/ \-------/+---  count(0-255)
+     *         |    +---------------  duration of step(8)
+     *         +--------------------  index of step table(0-31)
+     */
+    static union {
+        uint16_t row;
+        struct {
+            uint8_t count:8;
+            uint8_t duration:3;
+            uint8_t index:5;
+        } pwm;
+    } timer = { .row = 0 };
+
+    timer.row++;
+    
+    // LED on
+    if (timer.pwm.count == 0) {
+        led_set(1<<USB_LED_CAPS_LOCK);
+    }
+    // LED off
+    if (timer.pwm.count == pgm_read_byte(&breathing_table[timer.pwm.index])) {
+        led_set(0);
+    }
+}
diff --git a/common/sleep_led.h b/common/sleep_led.h
new file mode 100644
index 00000000..aebdbeaa
--- /dev/null
+++ b/common/sleep_led.h
@@ -0,0 +1,10 @@
+#ifndef SLEEP_LED_H
+#define SLEEP_LED_H
+
+#define NO_SUSPEND_POWER_DOWN
+
+void sleep_led_init(void);
+void sleep_led_enable(void);
+void sleep_led_disable(void);
+
+#endif
diff --git a/keyboard/gh60/Makefile.lufa b/keyboard/gh60/Makefile.lufa
index a5ff609a..8042ff3f 100644
--- a/keyboard/gh60/Makefile.lufa
+++ b/keyboard/gh60/Makefile.lufa
@@ -103,6 +103,7 @@ BOOTMAGIC_ENABLE = yes	# Virtual DIP switch configuration(+1000)
 MOUSEKEY_ENABLE = yes	# Mouse keys(+4700)
 EXTRAKEY_ENABLE = yes	# Audio control and System control(+450)
 CONSOLE_ENABLE = yes	# Console for debug(+400)
+SLEEP_LED_ENABLE = yes  # Breathing sleep LED during USB suspend
 #NKRO_ENABLE = yes	# USB Nkey Rollover - not yet supported in LUFA
 #PS2_MOUSE_ENABLE = yes	# PS/2 mouse(TrackPoint) support
 
diff --git a/protocol/lufa/lufa.c b/protocol/lufa/lufa.c
index 98c3a68f..127dece5 100644
--- a/protocol/lufa/lufa.c
+++ b/protocol/lufa/lufa.c
@@ -36,12 +36,20 @@
   this software.
 */
 
+#include <avr/sleep.h>
+#include <avr/wdt.h>
 #include "report.h"
 #include "host.h"
 #include "host_driver.h"
 #include "keyboard.h"
+#include "action.h"
+#include "matrix.h"
+#include "led.h"
 #include "sendchar.h"
 #include "debug.h"
+#ifdef SLEEP_LED_ENABLE
+#include "sleep_led.h"
+#endif
 
 #include "descriptor.h"
 #include "lufa.h"
@@ -133,16 +141,45 @@ static void Console_Task(void)
 /*******************************************************************************
  * USB Events
  ******************************************************************************/
-/** Event handler for the USB_Connect event. */
+/*
+ * Event Order of Plug in:
+ * 0) EVENT_USB_Device_Connect
+ * 1) EVENT_USB_Device_Suspend
+ * 2) EVENT_USB_Device_Reset
+ * 3) EVENT_USB_Device_Wake
+*/
 void EVENT_USB_Device_Connect(void)
 {
+    led_set(0x1f);  // all on
 }
 
-/** Event handler for the USB_Disconnect event. */
 void EVENT_USB_Device_Disconnect(void)
 {
 }
 
+void EVENT_USB_Device_Reset(void)
+{
+}
+
+void EVENT_USB_Device_Suspend()
+{
+#ifdef SLEEP_LED_ENABLE
+    sleep_led_enable();
+#endif
+}
+
+void EVENT_USB_Device_WakeUp()
+{
+    // initialize
+    matrix_init();
+    clear_keyboard();
+
+#ifdef SLEEP_LED_ENABLE
+    sleep_led_disable();
+#endif
+    led_set(host_keyboard_leds());
+}
+
 void EVENT_USB_Device_StartOfFrame(void)
 {
     Console_Task();
@@ -466,17 +503,83 @@ static void SetupHardware(void)
     USB_Device_EnableSOFEvents();
 }
 
+
+static bool wakeup_condition(void)
+{
+    matrix_scan();
+    for (uint8_t r = 0; r < MATRIX_ROWS; r++) {
+        if (matrix_get_row(r)) return true;
+    }
+    return false;
+}
+
+#define wdt_intr_enable(value)   \
+__asm__ __volatile__ (  \
+    "in __tmp_reg__,__SREG__" "\n\t"    \
+    "cli" "\n\t"    \
+    "wdr" "\n\t"    \
+    "sts %0,%1" "\n\t"  \
+    "out __SREG__,__tmp_reg__" "\n\t"   \
+    "sts %0,%2" "\n\t" \
+    : /* no outputs */  \
+    : "M" (_SFR_MEM_ADDR(_WD_CONTROL_REG)), \
+    "r" (_BV(_WD_CHANGE_BIT) | _BV(WDE)), \
+    "r" ((uint8_t) ((value & 0x08 ? _WD_PS3_MASK : 0x00) | \
+        _BV(WDIE) | (value & 0x07)) ) \
+    : "r0"  \
+)
+
 int main(void)  __attribute__ ((weak));
 int main(void)
 {
     SetupHardware();
     keyboard_init();
     host_set_driver(&lufa_driver);
+#ifdef SLEEP_LED_ENABLE
+    sleep_led_init();
+#endif
     sei();
 
-    // TODO: can't print here
-    debug("LUFA init\n");
     while (1) {
+        // while suspend
+        while (USB_DeviceState == DEVICE_STATE_Suspended) {
+#ifndef NO_SUSPEND_POWER_DOWN
+            // Enable watchdog to wake from MCU sleep
+            cli();
+            wdt_reset();
+
+            // Watchdog Interrupt and System Reset Mode
+            //wdt_enable(WDTO_1S);
+            //WDTCSR |= _BV(WDIE);
+            
+            // Watchdog Interrupt Mode
+            wdt_intr_enable(WDTO_120MS);
+            
+            // TODO: more power saving
+            // See PicoPower application note
+            // - I/O port input with pullup
+            // - prescale clock
+            // - BOD disable
+            // - Power Reduction Register PRR
+            // sleep in power down mode
+            set_sleep_mode(SLEEP_MODE_PWR_DOWN);
+            sleep_enable();
+            sei();
+            sleep_cpu();
+            sleep_disable();
+
+            // Disable watchdog after sleep
+            wdt_disable();
+#endif
+
+            // Send request of USB Wakeup from Suspend to host
+            if (USB_Device_RemoteWakeupEnabled) {
+                if (wakeup_condition()) {
+                    USB_Device_SendRemoteWakeup();
+                }
+            }
+        }
+
         keyboard_task();
 
 #if !defined(INTERRUPT_CONTROL_ENDPOINT)
@@ -484,3 +587,20 @@ int main(void)
 #endif
     }
 }
+
+#ifndef NO_SUSPEND_POWER_DOWN
+/* watchdog timeout */
+ISR(WDT_vect)
+{
+    /* wakeup from MCU sleep mode */
+/*
+    // blink LED
+    static uint8_t led_state = 0;
+    static uint8_t led_count = 0;
+    led_count++;
+    if ((led_count & 0x07) == 0) {
+        led_set((led_state ^= (1<<USB_LED_CAPS_LOCK)));
+    }
+*/
+}
+#endif