Chronic insomnia linked to higher risk of stroke, dementia and hospitalisation, shows study of 1.3 million people

A comprehensive analysis, published on 7 September in the scientific journal Sleep Medicine Reviews and based on data from over 1.3 million participants, shows that chronic insomnia is associated with a higher risk of stroke, hospitalisation, dementia, depression, and suicidal behaviour. The researchers note, however, that these additional risks are moderate and that insomnia can be treated. The study did not identify an increased risk of overall mortality among people with insomnia.

Specifically, people with insomnia had a 26% higher risk of suffering a stroke and a 28% greater likelihood of being hospitalised, regardless of the reason. The study's authors caution that these are statistical associations, not evidence that insomnia directly causes these conditions.

What constitutes chronic insomnia

Occasional sleep problems — caused by stress, pain, illness, hormonal changes, or starting a new medication — do not necessarily indicate a lasting disorder. Insomnia becomes chronic when difficulty falling asleep, repeated night-time awakenings, or waking too early occur at least three nights per week for a minimum of three months, and affect daytime functioning.

Alexandria Muench, Assistant Clinical Professor of Psychiatry at the University of Pennsylvania, explained to Newsweek that an episode of insomnia may be triggered by a stressful event, but can be perpetuated by habits such as spending too long in bed, worrying about sleep, or trying to force oneself to fall asleep.

Orfeu Buxton, Professor of Biobehavioural Health at Pennsylvania State University, noted that chronic insomnia typically arises from an interplay of several factors — genetic predisposition, work-related stress, conflicts, or other difficult circumstances — compounded by behaviours that sustain the problem. He also pointed out that certain unhealthy habits can simultaneously worsen insomnia.

Why insomnia may be linked to stroke risk

One possible explanation for the identified association is the link between sleep disorders and high blood pressure, a significant risk factor for stroke. Alexandria Muench noted that people with insomnia may be more likely to develop hypertension, but the two conditions may also share common causes, such as stress and certain lifestyle habits, meaning insomnia cannot automatically be considered a direct cause of stroke.

With regard to dementia, researchers are considering the role of sleep in the brain's clearance of waste substances, including proteins associated with Alzheimer's disease. Some research suggests that poor-quality sleep may impair this process, but the mechanisms are still being studied, and the findings do not indicate that insomnia inevitably leads to dementia.

The link with depression and suicidal behaviour

The relationship between sleep and mental health works in both directions: sleep disorders can make it harder to manage emotions, whilst anxiety, depression, and persistent worry can in turn make it harder to fall or stay asleep. According to Alexandria Muench, nights spent lying awake can amplify anxiety and reduce a person's ability to cope with difficulties, and in some situations these challenges may be associated with a higher risk of impulsive behaviour, including self-harm. However, the analysis does not establish a direct causal relationship between insomnia and these manifestations.

The researchers also identified a link between insomnia and a greater likelihood of hospitalisation. Muench explained that sleep difficulties can, in some cases, be a signal of pre-existing health problems rather than necessarily the cause of admission. She further noted that studies of this kind cannot prove that insomnia caused the conditions examined, and that in some of the included research, the association with certain health problems weakened or disappeared after accounting for the use of sleep medications.

What people with insomnia can do

Specialists emphasise that the additional risks identified were moderate and that chronic insomnia can be treated — persistent sleep problems should not be ignored, but they do not automatically mean the onset of serious illness. Orfeu Buxton stressed that insomnia is not an inevitable consequence of ageing. Prioritising sleep, taking regular physical exercise, maintaining a balanced diet, and managing stress can all contribute to better rest.

Alexandria Muench highlighted cognitive behavioural therapy for insomnia as one of the effective treatment options, and noted that in certain cases a doctor may also recommend sleep medication, depending on the individual's circumstances.

To improve sleep, specialists recommend several practical measures:

• A regular schedule: waking at the same time every day, including at weekends, helps stabilise the sleep rhythm.
• Going to bed only when sleepy: trying to force sleep can increase frustration and anxiety.
• Limiting daytime sleep: if a daytime nap affects night-time rest, it should be kept to no more than 30 minutes and avoided after 3:00 pm.
• Consulting a specialist: if sleep problems persist for several months or affect daily activities, they should be discussed with a doctor.

The analysis concludes that chronic insomnia deserves to be taken seriously, without being viewed as a sentence to serious health problems. Identifying the underlying causes and accessing appropriate treatment can improve both sleep and quality of life.