Five in the morning is where the British day genuinely starts moving. The first trains of the timetable go out from the big depots, the earliest gyms unlock their doors, radio breakfast teams are already at desks preparing bulletins, and postal sorting offices are working through the day's volume.
It is also the hour a lot of people choose deliberately. Early running and swimming, revision before work, and the quiet stretch before a household wakes up all have a following, particularly in summer when it is already light. In midwinter the same alarm means an hour and a half of darkness before sunrise.
For anyone travelling, 5 am is the classic departure time for a coach to an airport or a drive that needs to be finished before the motorways clog. Counting down to it accurately matters more than for most hours, because there is rarely any slack in a plan built around it.
Common questions
Why is 5 am such a common alarm time?
It suits early shifts, airport departures and anyone wanting an hour to themselves before the rest of the household is up.