Online alarm clock for 4:40 am
Prepare for the little penguin colony watch change before you need to move: set the alarm for 4:40 am while checking your warm layers, torch and keys. That leaves the final part of the night organised rather than rushed, with 20 minutes available before 5:00 am for gathering anything that must go with you.
A watch change can involve wind, conversation or equipment noise, so choose a signal volume you can hear above the sounds expected around you. Test it from the same distance and with the same background noise you will have while waiting. Keep a separate backup for the penguin watch, because this browser alarm will not sound once its page is closed or the computer has gone to sleep.
Getting ready at 4:40 am can easily disturb other people in the house, particularly when bags, doors and alarms are involved. Lay out clothing and equipment earlier, keep the phone close enough to use a moderate volume, and stop the signal promptly. If someone else is sleeping nearby, vibration alongside a quieter tone can make the wake-up more contained while still marking the moment to leave.