Wake up Reminders

I was preparing to go to bed, so I was setting my alarm clock in my hp. Knowing that if I am very tired, I will just off the alarm even without me knowing, I set reminders in my hp as well. The reminder will be named "Wake up". Just as I wanted to set the reminder, the following appears on my hp, " Memory Full. Clear old reminders?"

And guess what? Out of the 10 reminders, 8 in my hp are all titled, " Wake up."