How to use the online alarm clock
As you hand your remaining work to a colleague before leaving for an NHS blood donation appointment, set the alarm for 5:39 pm so the changeover does not swallow your departure time. It gives you a clear cue to finish the handover, gather your appointment details and head towards the donor centre. If you need to leave closer to 6:00 pm, treat that as a separate deadline rather than assuming you will notice the clock.
Your NHS blood donation plans depend on hearing the signal, so check it well before 5:39 pm: choose the sound, set a comfortable volume and run a brief test while there is still time to adjust it. Keep this page active after the test. This browser alarm cannot alert you once its active session has ended or the system has gone to sleep, which could leave the donation handover running late without a warning.
After an afternoon changeover, fading daylight can make papers, keys and travel details harder to spot just as you need to leave. Before returning to the handover, switch on a nearby lamp and place everything for the NHS appointment within that pool of light. By 5:39 pm, the alarm then marks a simple exit: finish the final sentence, pick up the visible items and go.
Common questions
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.
Can I use this on a phone?
It works in a mobile browser, but phones lock the screen and suspend background tabs far more readily than a laptop does, which can stop the alarm sounding. For anything important, a desktop or a plugged-in laptop is the steadier option.
Does the alarm still work if I close the tab?
No. Everything runs inside this page, so closing the tab — or quitting the browser altogether — ends the countdown there and then. Leaving it open in the background is all it asks, and switching to another tab makes no difference.
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