Why do we forget things?

We’ve all had those moments where we can’t quite remember something.

Maybe you’ve misplaced your keys, can’t remember someone’s name or just completely forgotten what it was that you were supposed to be doing.

A lapse in memory is a common thing, but why does it happen? BBC Bitesize explores how our memories work and why we forget things.

Short-term v long-term

If you’ve ever spent days revising for an exam only to forget that crucial fact, you might be wondering how that could actually happen.

Dr Liz Coulthard, associate professor in dementia neurology at the University of Bristol, explains that there’s a big difference between our short term and long term memories.

She said: “If you remember things just for a few seconds, like a phone number, you do it almost by rehearsal. You might visually imagine it, or repeat it to yourself. Short-term memory works like that, it’s a loop.

“For longer term memories, they all have to be laid down or stored, so the first thing that happens is they go into an area of the brain called the hippocampus.”

If you were to remember the start of a conversation the following day, that is down to a change in your brain structure.

When you form a new memory, your nerve fibres and synapses within the hippocampus are altered. The changing of the synapses is a process known as synaptic plasticity. Once a memory is laid down in your hippocampus, you don’t have to actively remember it or recall it to keep it there.

What happens next isn’t necessarily down to the individual themselves. The memory is strengthened or forgotten in the background, often while we sleep.

Remember how to remember…

So we know how to store our memories in the first place – but what is it that makes things pop out of our heads? Here are some of Dr Coulthard's top tips:

• Remain focused. If you're not fully paying attention, you'll struggle to retain information.
• Try to relax. Stress is not great for memory and if you start worrying and thinking about the process of thinking, it can impair your ability to lay down new memories.
• Sleep well. Making sure you get a good night's sleep on a regular basis can help to improve your memory.
• Eat regular meals. Ever get 'hangry'? Being hungry can be one of the worst types of distraction - and we know distractions can stop us from remembering things.
• Prioritise. The more you have to do, the more you're likely to forget, so being very busy can affect memories. Make sure you're not taking too many things on.

Improving your memory

When it comes to revision, students may have vastly different experiences with trying to remember important information for exams.

The way our brain works is defined by many things - from our education to how we developed as children. Part of it is our genetics too.

Our brains and memories can also be affected by other conditions – in particular, things that affect the heart. High blood pressure or cholesterol can affect the blood vessels in the brain as well, which can make it harder to recall some memories.

But it’s a common misconception that memory is automatically directly linked to intelligence.

“We all have an individual profile,” said Dr Coulthard. “I will forget things and have to have strategies to try to remember them."

There are things you can try, in order to attempt to improve your memory. One well-known technique is a memory palace.

In order to remember key bits of information, you associate them with specific, familiar locations. It's a memory technique dating back to ancient Greece - as you subsequently take an imaginary stroll through a location, you can place things you want to remember along the way and recall them on future memory journeys.

Whatever method you choose to help to remember things, Dr Coulthard said repetition is key.

“If you’ve seen something more than once, you’re more likely to remember it.

“People who do memory palace techniques link things together and that’s something that memory is absolutely designed to do. It’s designed to take two pieces of information and put them into your knowledge map.

“Make sure you get good sleep and remove your distractions too.”