Can't remember where you left your keys? Check how you're sleeping

From restless nights to oversleeping, irregular sleep habits make your brain age faster, raising the risk of forgetfulness, cognitive decline, and even dementia, says a new study

Forgetfulness, brain fog, or struggling to recall names may not just be signs of ageing, they could be symptoms of how well you are sleeping. A new global study has found that people with sleep disturbances, including poor sleep quality, or even sleeping too little or too long, face a sharply higher risk of cognitive decline and dementia.

 

Published in the Journal of Neurology, the study, titled Sleep disorders and the risk of cognitive decline or dementia: an updated systematic review and meta-analysis of longitudinal studies, analysed data from 76 cohort studies and found that poor sleep habits can raise the likelihood of Alzheimer’s disease and vascular dementia by up to two and a half times.

 

 

What did the study discover?

 

This analysis of more than seventy studies covering various categories of sleep disorders found that disrupted sleep was a powerful, independent risk factor for cognitive decline. The analysis found that:

• People with insomnia had a 13 per cent higher risk of developing dementia.
• Those sleeping less than 7 hours a night faced a 27 per cent higher risk of cognitive decline.
• Those sleeping more than 8 hours were at even greater risk, with a 43 per cent higher likelihood of all-cause dementia and a 66 per cent higher risk of Alzheimer’s disease.
• Excessive daytime sleepiness is associated with an 85 per cent higher risk of vascular dementia.
• Sleep-related movement disorders (like restless legs) doubled the risk of vascular dementia.
• Even poor sleep quality, independent of duration, raised the likelihood of Alzheimer’s and general cognitive decline.

According to the researchers, sleep is the brain’s housekeeping shift. During deep, restorative sleep, the brain clears out metabolic waste, particularly harmful proteins like beta-amyloid and tau, which are hallmarks of Alzheimer’s disease. Disturbed sleep disrupts this cleaning cycle, allowing toxic build-up, increased oxidative stress, and reduced melatonin levels, all of which impair cognitive health.  ALSO READ| Irregular sleep may trigger 172 diseases, warns biohacker Bryan Johnson 

Can fixing sleep really protect against dementia?

 

The researchers argue that it can. Unlike genetics or age, sleep is a modifiable risk factor. Addressing it early, through screening, lifestyle interventions, or medical treatment, could potentially delay or even prevent the onset of dementia in millions.

 

Practical steps include maintaining a consistent sleep schedule, limiting caffeine and blue light exposure, managing stress, and seeking medical help for persistent insomnia or sleep apnoea. Cognitive behavioural therapy for insomnia (CBT-I) remains the most effective non-drug treatment.