You cover all bases to try and stay sharp: Finish the crossword, crack open a book, hit the gym. And you probably do your best to avoid the big brain-rotters, like watching TV for hours on end.

But there are also draining habits you didn’t know would hurt your head. Check out these five.

1. Worrying about money

Being preoccupied with financial concerns can cause you to make slower and less responsible decisions while lowering your ability to focus, according to a 2013 study in the journal Science.

“Our minds have limited bandwidth – there’s only so much we can think about at any one time,” explains study author Eldar Shafir, PhD.

To free up brain space, try free online tools like Mint.com or Simple.com, or focus on reducing the other stressors in your life. Reduce the number of things you have to keep track of, and you’re giving yourself a “bandwidth gift”, which allows you to do other things better, he explains.

Read more: The best money advice we’ve ever overheard

2. Limiting your social circle

People with a larger network of friends have brains with bigger, better-connected regions responsible for decision-making and tracking other’s actions, reports a study from Oxford University. People with more friends may use certain parts of their brains more frequently, and the brain adapts to step up to that challenge, researchers speculate.

Chat up your neighbour or reconnect with varsity mates. Lonely people have a 64% greater risk of developing dementia, according to a 2012 Dutch study.

3. Using a GPS

A 2011 study from University College London found that cab drivers who navigated the complex layout of London’s streets from experience had higher levels of grey matter in the hippocampus, which caused them to have a better memory. What’s more, the taxi drivers were not predisposed to having high levels of grey matter, but instead acquired it. Researchers speculate that any mentally challenging task would change your brain’s structure to increase your recall.

4. Powering through sleepiness

Naps may look lazy, but catching sleep during the day could actually boost brainpower. A German study found that participants who took a 40-minute nap after studying performed up to 85% better on a memory test than non-nappers. Sleeping right after learning could help speed the process of retaining information.

It is still unclear how long the perfect nap should last: in one study from the University of California, Berkeley, people who napped for 90 minutes showed significant improvements in memory. But Australian research suggests even naps that last a few minutes can increase alertness.

Read more: The best time to take a power nap

5. Sticking to the same hobbies

Your brain responds to workouts the same way your muscles do. When you try something new, it becomes stronger. But after constant exposure to the same routine, your ability to bulk up peaks unless you switch to harder tasks.

That’s what a study from the Mind Research Network found: When participants were first taught Tetris, their brain used more glucose – which gives your brain energy – and bulked up their number of neural connections, representing learnt expertise.

After the initial cognitive boost, participants saw a decline in glucose consumption and neural connections. They remained just as skilled at Tetris, but their brains got more efficient and stopped benefiting from what was once a challenge. Just like you start a new workout plan every few weeks, you should also try a new hobby.

Read more: 6 hacks to kickstart your creativity and brainpower when you’re feeling sluggish

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