Your brain is responsible for everything you do. It processes information, stores memories, and shapes who you are.
Yet, many of us unknowingly engage in daily habits that can damage our brains over time.
From poor food choices to lack of sleep, these behaviours may accelerate cognitive decline and affect mental sharpness.

Here’s what science says are the five worst habits for brain health, and why it’s worth paying attention.

 

Eating processed foods

Sweet and savoury snacks, confectionery, cereals, ice cream, sweetened beverages, processed meats, and ready-to-eat frozen meals make up around 58% of calories in the average UK and US diet.^[1] These ultra-processed foods are convenient, affordable, and readily available – but they’re also high in unhealthy fats, sugars, and additives, which can trigger inflammation and oxidative stress in the brain.

A 2022 study of nearly 11,000 adults found that those with the highest intake of ultra-processed foods experienced a 28% faster decline in cognition and a 25% faster decline in everyday mental skills.^[2] Neuroimaging studies have suggested that eating these foods regularly may lead to shrinkage in gray matter volume, particularly in the left hippocampus. Processed foods are linked to increased levels of circulating proinflammatory cytokines and oxidative stress. Chronic neuroinflammation can impair axonal regeneration, neuronal regrowth, and remyelination, resulting in neurological dysfunction.^[3] Even short exposures to high-fat, high-sugar diets are found to impair memory.^[4]

 

Not getting enough sleep

We all know it’s harder to think properly when we’re tired, but it’s only recently that research has shown how a lack of sleep affects the brain.

During sleep, the brain processes and consolidates memories, strengthens neural connections and integrates new information.^[5] Sleep deprivation has been shown to create an imbalance between areas of the brain known as the task-related default mode network and the frontoparietal network, both of which play important roles in focus and attention. Consistent lack of sleep can lead to irregular neural activity, affecting concentration and working memory.^[6]

Sleep-deprived individuals are slower and less precise in cognitive tasks, with reduced activation in key brain regions such as the parahippocampal place area (which processes and recognises visual scenes) and the frontoparietal cortex (which coordinates working memory, task switching, and decision-making).^[7] PET scans have also revealed decreased activity in the thalamus and prefrontal cortex, regions essential for sustained attention, likely due to altered glucose metabolism.^[8]

Sleep deprivation can also cause brief “off periods” in cortical neurons during waking hours, in which they stop firing. This can lead to lapses in focus and cognitive function.^[9]

 

Excessive screen time

Hours of scrolling social media may be affecting our brains – and our attention span.

Recent studies suggest that extensive online media usage may have detrimental effects on cognitive development, especially in the younger generation. High levels of Internet usage and heavy media multitasking are associated with decreased grey matter in prefrontal regions associated with maintaining goals when faced with distractions.^[10]

People who engage in excessive online activities (including general surfing, gaming, gambling, shopping, social networking) are also found to have structural brain changes and reduced grey matter in several areas, including prefrontal and orbitofrontal cortical layers involved in decision-making, planning, and emotional regulation.^[11]

Too much online time during brain developmental years may even lead to “digital dementia”.^[12]

Further studies have shown that even short‐term engagement with an extensively hyperlinked online environment – such as a shopping site – reduces attentional scope for sustained periods after going offline. Other cognitive activities, such as reading a book, do not cause these deficits.^[13]

 

Cigarettes and alcohol

Cigarette smoking doesn’t just affect the lungs – it can cause severe abnormalities in brain function. A 2023 study found that smoking had a cumulative effect on cognitive decline, which means that the greater the exposure, the higher the decline. Even light smokers and former smokers were affected by cognitive decline.^[14]

Chronic smoking is strongly linked to cerebral small vessel damage and may also accelerate white matter degeneration, which can be an early sign of dementia and mild cognitive impairment.^[15] Smoking may also disrupt genes involved in normal myelin production and maintenance.^[16]

Alcohol also has a significant impact on mood and cognition. Alcohol is also a major cause of hypertension, a key risk factor for dementia.^[17] High blood pressure can lead to arterial heart disease and hypoperfusion, which affects the delivery of oxygen to the brain, potentially leading to neuronal injury.^[18]

Large amounts of alcohol may be metabolised to acetaldehyde, further contributing to brain injury or nutritional deficiency.^[19] Excess alcohol weakens the brain’s protective barrier, making it more vulnerable to damage and inflammation.^[20]

 

Your daily habits shape your brain health, often in ways you don’t notice until later in life. But small changes now can help keep your mind sharp for years to come.

 

This information is provided for educational purposes only and is not a substitute for professional medical advice. Always seek the guidance of your physician or qualified healthcare provider with any questions you may have regarding your health or a medical condition.

 

References

 

^[1] Martínez Steele, E., Baraldi, L. G., Louzada, M. L., Moubarac, J. C., Mozaffarian, D., & Monteiro, C. A. (2016). Ultra-processed foods and added sugars in the US diet: evidence from a nationally representative cross-sectional study. BMJ open, 6(3), e009892. https://doi.org/10.1136/bmjopen-2015-009892

^[2] Gomes Gonçalves, N., Vidal Ferreira, N., Khandpur, N., Martinez Steele, E., Bertazzi Levy, R., Andrade Lotufo, P., Bensenor, I. M., Caramelli, P., Alvim de Matos, S. M., Marchioni, D. M., & Suemoto, C. K. (2023). Association Between Consumption of Ultraprocessed Foods and Cognitive Decline. JAMA neurology, 80(2), 142–150. https://doi.org/10.1001/jamaneurol.2022.4397

^[3] Ghanim, H., Abuaysheh, S., Sia, C. L., Korzeniewski, K., Chaudhuri, A., Fernandez-Real, J. M., & Dandona, P. (2009). Increase in plasma endotoxin concentrations and the expression of Toll-like receptors and suppressor of cytokine signaling-3 in mononuclear cells after a high-fat, high-carbohydrate meal: implications for insulin resistance. Diabetes care, 32(12), 2281–2287. https://doi.org/10.2337/dc09-0979

^[4] Beilharz, J. E., Maniam, J., & Morris, M. J. (2014). Short exposure to a diet rich in both fat and sugar or sugar alone impairs place, but not object recognition memory in rats. Brain, behavior, and immunity, 37, 134–141. https://doi.org/10.1016/j.bbi.2013.11.016

^[5] Walker M. P. (2009). The role of slow wave sleep in memory processing. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 5(2 Suppl), S20–S26.

^[6] Wang, Y., Liu, H., Hitchman, G., & Lei, X. (2015). Module number of default mode network: inter-subject variability and effects of sleep deprivation. Brain research, 1596, 69–78. https://doi.org/10.1016/j.brainres.2014.11.007

^[7] Fox, M. D., & Raichle, M. E. (2007). Spontaneous fluctuations in brain activity observed with functional magnetic resonance imaging. Nature reviews. Neuroscience, 8(9), 700–711. https://doi.org/10.1038/nrn2201

^[8] Fox, M. D., & Raichle, M. E. (2007). Spontaneous fluctuations in brain activity observed with functional magnetic resonance imaging. Nature reviews. Neuroscience, 8(9), 700–711. https://doi.org/10.1038/nrn2201

^[9] Timofeev I. (2011). Neuronal plasticity and thalamocortical sleep and waking oscillations. Progress in brain research, 193, 121–144. https://doi.org/10.1016/B978-0-444-53839-0.00009-0

^[10] Loh, K. K., & Kanai, R. (2014). Higher media multi-tasking activity is associated with smaller gray-matter density in the anterior cingulate cortex. PloS one, 9(9), e106698. https://doi.org/10.1371/journal.pone.0106698

^[11] Tereshchenko S. Y. (2023). Neurobiological risk factors for problematic social media use as a specific form of Internet addiction: A narrative review. World journal of psychiatry, 13(5), 160–173. https://doi.org/10.5498/wjp.v13.i5.160

^[12] Laurie A. Manwell, Merelle Tadros, Tiana M. Ciccarelli, Roelof Eikelboom. Digital dementia in the internet generation: excessive screen time during brain development will increase the risk of Alzheimer’s disease and related dementias in adulthood. J. Integr. Neurosci. 2022, 21(1), 28. https://doi.org/10.31083/j.jin2101028

^[13] Peng, M., Chen, X., Zhao, Q., & Zhou, Z. (2018). Attentional scope is reduced by Internet use: A behavior and ERP study. PloS one, 13(6), e0198543. https://doi.org/10.1371/journal.pone.0198543

^[14] Benito-León, J., Ghosh, R., Lapeña-Motilva, J., Martín-Arriscado, C., & Bermejo-Pareja, F. (2023). Association between cumulative smoking exposure and cognitive decline in non-demented older adults: NEDICES study. Scientific reports, 13(1), 5754. https://doi.org/10.1038/s41598-023-32663-9

^[15] Hamilton, O. K. L., Cox, S. R., Okely, J. A., Conte, F., Ballerini, L., Bastin, M. E., Corley, J., Taylor, A. M., Page, D., Gow, A. J., Muñoz Maniega, S., Redmond, P., Valdés-Hernández, M. D. C., Wardlaw, J. M., & Deary, I. J. (2021). Cerebral small vessel disease burden and longitudinal cognitive decline from age 73 to 82: the Lothian Birth Cohort 1936. Translational psychiatry, 11(1), 376. https://doi.org/10.1038/s41398-021-01495-4

^[16] Yu, R., Deochand, C., Krotow, A., Leão, R., Tong, M., Agarwal, A. R., Cadenas, E., & de la Monte, S. M. (2016). Tobacco Smoke-Induced Brain White Matter Myelin Dysfunction: Potential Co-Factor Role of Smoking in Neurodegeneration. Journal of Alzheimer’s disease : JAD, 50(1), 133–148. https://doi.org/10.3233/JAD-150751

^[17] Livingston, G., Sommerlad, A., Orgeta, V., Costafreda, S. G., Huntley, J., Ames, D., Ballard, C., Banerjee, S., Burns, A., Cohen-Mansfield, J., Cooper, C., Fox, N., Gitlin, L. N., Howard, R., Kales, H. C., Larson, E. B., Ritchie, K., Rockwood, K., Sampson, E. L., Samus, Q., … Mukadam, N. (2017). Dementia prevention, intervention, and care. Lancet (London, England), 390(10113), 2673–2734. https://doi.org/10.1016/S0140-6736(17)31363-6

^[18] Qiu, C., Winblad, B., & Fratiglioni, L. (2005). The age-dependent relation of blood pressure to cognitive function and dementia. The Lancet. Neurology, 4(8), 487–499. https://doi.org/10.1016/S1474-4422(05)70141-1

^[19] Panza, F., Frisardi, V., Seripa, D., Logroscino, G., Santamato, A., Imbimbo, B. P., Scafato, E., Pilotto, A., & Solfrizzi, V. (2012). Alcohol consumption in mild cognitive impairment and dementia: harmful or neuroprotective?. International journal of geriatric psychiatry, 27(12), 1218–1238. https://doi.org/10.1002/gps.3772

^[20] Pervin, Z., & Stephen, J. M. (2021). Effect of alcohol on the central nervous system to develop neurological disorder: pathophysiological and lifestyle modulation can be potential therapeutic options foralcohol-induced neurotoxication. AIMS neuroscience, 8(3), 390–413. https://doi.org/10.3934/Neuroscience.2021021