We all like to think we’re innately pretty clever, but intelligence does actually need to be honed and nurtured.
Just as there are things you can do to increase your brain power, science has shown that certain behaviours, environments, and choices can actually reduce cognitive function over time. However, the good news is that many of these things are completely avoidable. If you have any of these bad habits, they could be lowering your intelligence without you even realising it, and it might be time to make a change.
1. Not getting enough sleep
Skipping sleep doesn’t just make you feel groggy — it actually messes with your brain function. Studies have found that sleep deprivation affects memory, problem-solving skills, and even emotional intelligence. When you’re running on empty, your ability to focus and process information takes a serious hit. Long-term sleep deprivation has even been linked to a decline in overall cognitive ability. Your brain needs rest to organise thoughts, store memories, and reset for the next day. If you’re cutting corners on sleep, you’re not just making yourself tired; you’re making yourself slower, too.
2. Eating too much processed food
That fast food habit might be doing more than just expanding your waistline. Research has shown that diets high in processed foods, sugar, and unhealthy fats can negatively impact brain function. These foods cause inflammation and oxidative stress, which can damage brain cells over time. A poor diet can also affect neurotransmitters, the chemicals responsible for communication between brain cells. If you’re constantly feeding your body low-quality fuel, don’t be surprised if your brain starts feeling sluggish, too. A diet rich in whole foods, healthy fats, and antioxidants is the way to go.
3. Relying too much on technology
We’ve all become a little too dependent on our phones and search engines. Need an answer? Just Google it. While technology is useful, constantly outsourcing our thinking can weaken memory and problem-solving skills. If you never exercise your brain, it loses its sharpness over time. Studies suggest that excessive smartphone use is linked to reduced attention spans and decreased cognitive control. Instead of instinctively reaching for your phone, try giving your brain a workout by recalling information, reading deeply, or engaging in real conversations.
4. Living a sedentary lifestyle
If you’re spending most of your day sitting, your brain might be paying the price. Physical activity is directly linked to the brain’s ability to function, and research shows that regular movement improves memory, attention, and problem-solving abilities. Exercise increases blood flow to the brain, which helps keep neurons healthy and encourages new brain cell growth. On the flip side, too much sitting has been associated with cognitive decline. Even if you’re not hitting the gym, small changes like walking more, stretching, or standing up frequently can help keep your brain in top shape.
5. Skipping socialising
Spending too much time alone, especially without meaningful conversations, can dull your thinking abilities. Social interactions engage multiple areas of the brain, improving memory, communication skills, and emotional intelligence. When we regularly interact with other people, we challenge our thinking, adapt to different perspectives, and sharpen our cognitive flexibility. On the other hand, isolation can lead to cognitive decline and even increase the risk of dementia. Even if you’re naturally introverted, engaging in stimulating conversations or being part of a community can make a difference in keeping your mind active.
6. Multitasking too often
It might feel like you’re getting more done, but multitasking actually makes you less efficient. Studies show that constantly switching between tasks reduces concentration, lowers memory retention, and slows down cognitive processing. Instead of mastering multiple things at once, your brain is just struggling to keep up. Over time, this habit can weaken your ability to focus on deep work and problem-solving. Instead of juggling ten things at once, try single-tasking — focusing on one thing at a time leads to better retention and higher-quality thinking.
7. Surrounding yourself with negativity
Constant exposure to stress, negativity, and toxic environments can actually shrink the brain. Research has found that chronic stress releases cortisol, which affects memory, learning ability, and emotional regulation. If you’re always in a stressful or negative space, your brainpower can take a real hit. Your brain thrives in a healthy, supportive environment. Whether it’s toxic relationships, too much negative news, or an overly stressful job, limiting your exposure to negativity can protect your mental sharpness.
8. Not challenging your brain
Your brain is like a muscle — if you don’t use it, you lose it. Engaging in mentally stimulating activities like reading, puzzles, learning a new skill, or even debating ideas helps strengthen cognitive function. Without these challenges, the brain becomes lazy, leading to a decline in problem-solving skills and memory. If you always stick to routine thinking and never step outside your intellectual comfort zone, your brain starts running on autopilot. Make it a habit to challenge yourself, whether it’s learning a new language, picking up a creative hobby, or simply thinking critically about different topics.
9. Overloading on alcohol
It’s no surprise that too much alcohol affects brain function, but even moderate drinking can impact memory and decision-making. Alcohol interferes with neurotransmitters and reduces brain plasticity, making it harder to process and retain information. Long-term heavy drinking has even been linked to brain shrinkage. That doesn’t mean you can’t enjoy a drink now and then, but excessive consumption over time can weaken cognitive performance. If you want to keep your brain sharp, moderation is key.
10. Ignoring mental health
Anxiety, depression, and chronic stress don’t just affect emotions; they impact your brain power, too. Studies have found that mental health issues can reduce focus, impair memory, and slow down processing speed. The longer these conditions go untreated, the more they can interfere with intelligence. Poor mental health can also make it harder to engage in intellectual activities, form new ideas, or retain information. Taking care of your mental well-being through therapy, self-care, or stress management techniques can help keep your brain functioning at its best.
11. Spending too much time indoors
Surprisingly, a lack of sunlight and fresh air can impact cognitive function. Studies show that vitamin D deficiency, which is common in people who don’t get enough sun exposure, is linked to lower cognitive performance and increased risk of memory problems. Spending time outdoors can boost brain function by improving mood, reducing stress, and increasing oxygen flow to the brain. Whether it’s a short walk or sitting in a park, getting outside more often can help keep your mind clear and focused.
12. Staying in a constant state of distraction
If you’re always scrolling, checking notifications, or jumping from one thing to another, your brain never gets a chance to fully engage. Constant distractions train your brain to function on surface-level thinking rather than deep concentration. Over time, this reduces your ability to focus for extended periods. Science suggests that frequent distractions can lower IQ points in the short term, similar to sleep deprivation. If you want to improve your cognitive abilities, setting aside distraction-free time for work, reading, or even quiet reflection can make a huge difference.
13. Not drinking enough water
It sounds simple, but dehydration can seriously mess with your brain. Even mild dehydration has been linked to reduced focus, memory problems, and slower reaction times. Since the brain is mostly water, it needs proper hydration to function properly. When you’re dehydrated, your cognitive performance takes a hit, making it harder to think clearly and stay productive. Keeping up with water intake throughout the day is an easy way to keep your brain working at full capacity.
