Catching the first train
The first Chicago "L" train of the day leaves at about 4:00 AM. If you are heading to the airport, an early shift, an exam or a flight connection, that first train is the one you cannot miss — the next one may be 10 to 20 minutes behind, and before dawn the gap is often wider. To be on the platform for 4:00 AM you need to be awake, dressed and out the door well before it, which in practice means an alarm going off in the dark.
The alarm is the part that fails
Almost nobody misses the first train because they mistimed the walk to the station. They miss it because the alarm went off and they turned it back off. In the first minutes after waking, the deciding part of your brain is still offline, and swiping an alarm away is a reflex you can perform in your sleep. An alarm that only stops once you complete a real task — walk to another room and scan a code, do the squats, solve the maths — forces you properly awake before your hand can cancel it, so a 4:00 AM train becomes a train you actually catch.
Times vary — check before an early trip
These are the network’s typical first and last services. Individual lines, branches and stations open and close at slightly different times; weekends, public holidays and engineering works can shorten the day or start it later. Before an early or late journey that really matters, confirm the exact first or last train for your station on the operator’s site or app.