Set the alarm clock for 5:35 am

Leave this tab open — the alarm only rings while the tab stays open.

The alarm goes off in: ::

You can also try the other alarm clocks

Alarm clock for 5:33 am Alarm clock for 5:34 am Alarm clock for 5:36 am Alarm clock for 5:37 am

Going to bed for a 5:35 am alarm

Asleep by 8:20 pm — 6 full sleep cycles, about 9 hours
Asleep by 9:50 pm — 5 full sleep cycles, about 7 hours
Asleep by 11:20 pm — 4 full sleep cycles, about 6 hours

A sleep cycle runs about 90 minutes, and most people take around 15 minutes to drop off. Waking at the end of a cycle feels easier than waking in the middle of one.

5:35 am across the country

London	5:35 am
Birmingham	5:35 am
Manchester	5:35 am
Glasgow	5:35 am
Belfast	5:35 am

Times are worked out live in your browser, so daylight saving is already accounted for.

How to use the online alarm clock

Finish checking the rail replacement timetable at 5:35 am, save the journey details you need, and then head out. An alarm set for 6:00 am can mark the point when travel preparations need to be complete, leaving 25 minutes for packing essentials, finding tickets and confirming which station entrance is open this early.

Your rail replacement timetable check deserves a tested signal rather than an alarm first heard when departure is already close. Set a brief trial alarm, keep the sound audible, and confirm that it plays before resetting it for 6:00 am. Do not rely on this browser alarm alone for the timetable check: it may fall silent after you leave the page or your phone goes to sleep, removing the prompt your journey depends on. A separate phone alarm provides a sensible backup.

Before leaving after an early timetable check, keep the screen dim enough for the dark surroundings but bright enough to read platform names and bus-stop details without squinting. Switching away from a stark white display can make the 5:35 am check feel less glaring. Once the essential journey information is saved, put the screen down and use the remaining time to gather your coat, ticket and keys.

Common questions

What happens if my laptop goes to sleep before 5:35 am?

The tab sleeps along with it and the alarm will not sound on time, if at all. If you are relying on it, change the power settings so the machine stays awake, or keep a phone alarm running as well.

Do I need an account or an app?

Neither. Choose a time and a sound, press Start, and it runs in this browser tab. Nothing is downloaded, nothing is registered, and closing the page leaves nothing behind on the device.

Can I change the sound?

Yes, there is a short list of tones to pick from before you press Start. Softer sounds are easy to sleep through, so a firmer bell tends to be the safer choice for anything early in the morning.

Will it still be right when the clocks change?

Yes. It reads your device's local clock, so the move between GMT and BST at the end of March and October is picked up automatically, as long as the computer's date, time and time zone are set correctly.