Light- or Modem Sleep

IMO that code should really go into jshSleep - if you look at the STM32 port it basically does:

void jshSleep(time) {
  if (deepSleepEnabled) {
    deep_sleep(time);
  } else {
    normal_sleep(time);
  }
}

I know it's a bit different in ESP8266, but it should still be possible to sleep in there - and then it behaves the same as other Espruino devices. You just call setDeepSleep(1) and from then on it does deep sleep whenever it can.