If you're feeling rather bleary eyed from a busy weekend, waking your brain up with a tricky optical illusion might just be the ticket.
Brain teasers challenge your sense of perception and force you to really concentrate on finding missing objects or hidden details, in turn helping improve your memory.
They are great fun to challenge friends and family with too - and the most competitive among us might even try and beat the puzzle against the clock to really get those brain juices flowing.
From hidden numbers to psychological tests that challenge you to spot the 'real' story behind the image, there's plenty of riddles to sink your teeth into. The latest optical illusion that has everyone scratching their heads comes in the form of a triangle - or many triangles, in fact.
This brain teaser, created by Rainbow Riches Casino, challenges you to spot all the hidden triangles within a larger triangle, and it's more difficult than it seems at first glance.
The green pyramid is full to the brim with various shapes and patterns, so hunting down all of the triangles within it should really put your skills to the test.
On average it takes six minutes for people to spot all of the triangles, so if you're struggling, you're not alone.
Only the brainiest bunch will decipher the shapes in less time, so kudos to you if you're already feeling ahead of the game with your triangle tally.
Some of them are quite obvious, but the more you gaze at all of the shapes, the more triangles come to the fore, making it rather mind-boggling.
Have you managed to spot them all? If you're struggling, the only tip we have is that there's more than you might think.
For those dying to know if they've got the answer right, we've revealed all below.
It turns out that there are 24 different triangles hidden in this clever brain teaser – how many did you find?
If you enjoyed this puzzle, why not challenge yourself to find the phone hidden in the sea of handbags in this tricky illusion.
You'll have to be quick, as only true geniuses can spot it in 35 seconds.
It's not just visual quizzes that have people in a spin, as one audio illusion has left people baffled too.
The bizarre audio sounds different to everyone, depending on what you think of, so why not give that a try and test your mates to see what they hear.
Did you manage to spot all the triangles in under six minutes? Tell us in the comments below.
