A global insomnia estimate built from 18 studies and 31 countries

Insomnia is described as common in almost every paper written about it, and until recently there was no global figure to attach to the word. A systematic review published in Sleep Medicine Reviews on 25 June produces one — and the interesting part is how much scaffolding it required.

How the estimate was built

The authors searched PubMed and Embase using the terms "insomnia", "prevalence" and "general population", with the final search on 2-3 September 2024 [s1]. They included only studies with the highest data quality and lowest risk of bias that reported clinically relevant insomnia prevalence in the general population [s1].

Of 1,651 potential records, 18 studies covering 262,582 participants met those criteria [s1].

Those 18 studies were then applied to United Nations population data, using a country-specific study where one existed and the highest-quality study where none did [s1]. Thirty-one of 237 UN or World Bank recognised countries and territories had a suitable nation-specific adult prevalence estimate [s1].

The resulting figures: 852,325,091 adults with insomnia (95% CI 830,354,161-874,309,252), a global prevalence of 16.2%, and 414,967,941 with severe insomnia, a prevalence of 7.9% [s1]. Insomnia and severe insomnia were more prevalent in females than males across all age groups [s1]. The review is registered as PROSPERO CRD42024581410 [s1].

What the precision does not mean

A figure quoted to the individual person — 852,325,091 — carries an implied precision that the method cannot support, and the paper's own description makes clear why. Fewer than one in seven countries contributed a national estimate [s1]. For the remaining 206 countries and territories, prevalence was imported from a study conducted somewhere else.

The confidence interval reflects sampling uncertainty within the included studies. It does not reflect the much larger uncertainty introduced by assuming that insomnia prevalence measured in one country applies to another with a different demographic structure, working culture, climate and health system.

That is not a flaw the authors conceal; it is a consequence of the evidence available, and the strict inclusion criteria that reduced 1,651 records to 18 are precisely what makes the underlying studies trustworthy and the extrapolation wide. The honest reading is that 16.2% is the best available central estimate from high-quality data, and that the number of decimal places is an artefact of multiplication.

The consistent female excess across all age groups is a more robust finding, because it is a within-study comparison repeated across the included studies rather than a between-country extrapolation [s1].

Why blood pressure belongs in the same conversation

A European Society of Hypertension position paper published on 12 June covers a different aspect of the same eight hours [s2].

Interest in nocturnal blood pressure has increased because of its strong association with cardiovascular risk, and its importance was recognised in the 2023 ESH guidelines [s2]. The paper describes nocturnal BP regulation as complex and multifactorial, involving the sleep-wake cycle, circadian rhythms, the autonomic nervous system, the renin-angiotensin-aldosterone system and renal mechanisms [s2].

Twenty-four-hour ambulatory blood pressure monitoring is currently the reference method for assessing nocturnal BP [s2]. Home monitoring with specially designed, validated devices that have a nocturnal measurement function may also be used, while new cuffless and wearable technologies are described as holding great potential but requiring further validation [s2]. That last clause is the one consumer sleep-tracking claims tend to omit.

The clinically relevant phenotypes are nocturnal hypertension, increased nocturnal BP variability and altered day-night BP fluctuation [s2]. Isolated nocturnal hypertension may be considered a type of masked hypertension — that is, normal in the clinic and abnormal at night [s2]. Both BP variability and the day-night change, known as dipping, carry prognostic relevance [s2].

Nocturnal hypertension and non-dipping are particularly prevalent in people with autonomic neuropathies, sleep disorders including obstructive sleep apnoea, kidney disease, and metabolic or endocrine disorders, and are linked to hypertension-mediated organ damage and cardiovascular risk [s2].

What is unresolved

The position paper is explicit that treatment strategies targeting nocturnal BP remain debated [s2]. Chronotherapy — evening dosing of antihypertensives — has shown inconsistent results in clinical trials [s2]. Renal denervation and treatment of sleep-related breathing disorders may lower nocturnal BP and improve sleep quality [s2]. The authors call for more research on pathophysiology, measurement, therapeutic intervention and overall management [s2].

This article describes what two documents report. It is not guidance about measuring or treating blood pressure, or about insomnia.

What to watch

Whether national prevalence surveys appear for countries currently represented only by imported estimates — the constraint that dominates the global insomnia figure [s1]. And whether cuffless and wearable nocturnal BP devices accumulate the validation the ESH says they currently lack [s2].

Sources

• [s1] Estimation of the global prevalence and burden of insomnia: a systematic literature review-based analysis. Sleep Medicine Reviews, 25 June 2025. https://doi.org/10.1016/j.smrv.2025.102121
• [s2] Nocturnal blood pressure: pathophysiology, measurement and clinical implications. Position paper of the European Society of Hypertension. Journal of Hypertension, 12 June 2025. https://doi.org/10.1097/HJH.0000000000004053