Hi dialog,
I modified ble_barebone app by changing app_default_sleep_mode=ARCH_EXT_SLEEP_ON to work in extended sleep mode .Configured an gpio for led indication.
I have kept an LED to indicate whether the device is in active mode or sleep mode editing the arch_main.c as follow:

sleep_mode = rwip_power_down();
GPIO_SetActive(GPIO_CNXN_LED_PORT, GPIO_CNXN_LED_PIN);
if ((sleep_mode == mode_ext_sleep) || (sleep_mode == mode_deep_sleep)) {
//power down the radio and whatever is allowed
GPIO_SetInactive(GPIO_CNXN_LED_PORT, GPIO_CNXN_LED_PIN);
arch_goto_sleep(sleep_mode);

//wait for an interrupt to resume operation
WFI();
//resume operation
arch_resume_from_sleep();
I observe the LED stays on always. how to increase the sleep period?