Arduino MKR series low power code

Hi,
I have a number of projects using the MKR 1400 gsm board and would like to reduce the power consumption when the processor is idling. The current code i use is:

setup() {
  if (sleeping==1) {
    USB->DEVICE.CTRLA.reg &= ~USB_CTRLA_ENABLE;

    // Set the alarm at the 5 second mark
    _RTC.setAlarmSeconds(5);
  
    // Match only seconds
    _RTC.enableAlarm(RTCZero::MATCH_SS);
  
    // Set sleep mode
    SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;
  }
}

void loop() {
  //do some stuff

  digitalWrite(LED, HIGH); digitalWrite(extLED, HIGH);
  delay(15);
  digitalWrite(LED, LOW); digitalWrite(extLED, LOW);

  if (sleeping==1) {

    __WFI();
    
    _RTC.setAlarmSeconds((_RTC.getAlarmSeconds() + 5) % 60);
    
  }
}

The above code will drop the current draw to about 20 mA during idle but i would like to get down to about 1- 5 mA max if possible. Is this doable?

Any help is much appreciated.

Cheers.

Any ideas on this?

Cheers.