Alarm clock

We had to get up early morning, at 5 to be in airport in time. I set my alarm clock to 5 but worried that something could happen and it will not work or I'll not hear it. I wanted to set second clock but there were no more alarm clocks at home.

I fell asleep... and see a dream - alarm clock which shows 5 and rings.

I awoke from the ring and looked at my (real) alarm clock - it was 7 minutes before 5!

So I managed to set second alarm clock in my brain!