Whether it's where you left your keys or why you walked into a room, there are often times when our memories fail us. 

But if you're regularly left scratching your head, you'll be happy to hear that help is at hand. 

A Cambridge scientist has revealed his ingenious memory trick - and it's deceptively simple. 

According to Professor Jon Simons, actively trying to remember something is what can stop the memory from being retrieved. 

Instead, he advises thinking about something else or finding a way to relax in order to retrieve memories.  

The head of the Cambridge University Memory Lab explained his memory trick on the Rosebud podcast. 

'What happens when we're really really trying to remember something, is often by that very effort block the memory from being retrieved,' he explained. 

'And it's only when that effort that we've put in gradually subsides and we maybe think about other things or we just calm down and relax that the memory is able to be retrieved.'

On the podcast, host Gyles Brandreth spoke about a time he remembered the name of someone he'd last thought of 55 years ago. 

In response, Professor Simons said: 'This phenomenon that you describe, the sort of tip of the tongue sensation it sounds like you had, where you know it's there but you can't quite bring it to mind, is a very common sensation that we all experience from time to time.

'That - the feeling you knew it was in there - suggests  it was one of those memories that for one reason or another had defied time and was something you remembered.

'And so that does happen, and then it is interesting how often you can puzzle and puzzle and puzzle over something and really, really try to remember it and struggle - and then the moment you think about something else, suddenly it pops into your head and that's quite a common experience.'