Sleep science barely covers 1.1 billion people. Two studies started filling the gap

Sub-Saharan Africa is home to 1.1 billion people, and sleep health in the region remains critically understudied [s1]. That sentence, from the opening of a paper in Sleep Health, describes a gap that most of the field's evidence base — cohorts, norms, thresholds, intervention trials — quietly assumes away.

Two studies published in the same journal this year begin to close it from different directions. One establishes what sleep health actually looks like across a national sample of Nigerian adults. The other asks what happens to sleep when the electricity supply becomes unreliable.

What a national baseline looks like

The Nigerian study used stratified random sampling to recruit 1,046 adults for a cross-sectional survey, with a mean age of 33·64 (SD 9·29), 62·4% male and 51·2% rural [s1]. Rather than measuring sleep duration alone, it applied the RU-SATED questionnaire v2.0, which assesses six dimensions of sleep health [s1].

The composite score averaged 6·31 (SD 2·15) [s1]. Compared against previously collected samples from Norway (n=1,028) and the United States (n=3,401), the Nigerian mean was significantly lower than both: Norway averaged 8·96 (SD 2·10, d=1·25) and the US 7·58 (SD 2·35, d=0·50), with p<0·001 for both comparisons [s1].

The dimension-level result is more informative than the composite. Only 16% to 22% of participants met the healthy threshold for regularity, efficiency and duration [s1] — meaning the shortfall is concentrated in when people sleep and how consolidated it is, not spread evenly across all six dimensions.

Within the sample, women and urban residents reported better overall sleep health (p=0·001), and age was positively correlated with the composite score (r=0·13, p<0·001) [s1].

Two of those associations run counter to what a reader might expect from higher-income settings, where sleep problems more often increase with age and where urban living is not usually protective. That is precisely the point of collecting the data rather than extrapolating.

The limits of the comparison

The cross-national contrast is the study's most quotable finding and its weakest. Norway, the US and Nigeria were sampled by different investigators at different times with different recruitment methods, and the RU-SATED thresholds themselves were developed in high-income settings. A lower score in Nigeria could reflect worse sleep, or an instrument whose cut-points fit the sampled population imperfectly, or both.

The design is also cross-sectional and entirely self-reported. There is no actigraphy, no polysomnography and no follow-up, so nothing here speaks to health outcomes. The authors frame the work as baseline data for the region and a case for contextually tailored interventions [s1], which is the appropriate weight to give it.

When the power goes out

The second study examines a variable that scarcely appears in sleep research conducted in countries with stable grids. South Africa's loadshedding — planned rolling power outages — removes household control over lighting and room temperature, while backup generator use adds noise [s2].

Researchers surveyed students at the University of the Witwatersrand during 2023, described as the worst year in the country's loadshedding history [s2]. An online questionnaire distributed to all registered students drew 1,124 responses, roughly 3% of the university population, with a mean age of 22 and 72% female [s2].

Among respondents, 73% said loadshedding affected their sleep, and 80% of those reported it was worse [s2]. The most frequently reported disruptions were increased sleep fragmentation (51%) and longer sleep onset latency (32%) [s2].

The study's most quantitative finding concerns backup power. Forty percent of students had access to an alternative power source, and that access was associated with an odds ratio of 0·43 (95% CI 0·32–0·56) for reporting worse sleep, in a multivariable logistic regression adjusted for age, sex, degree level, accommodation, ancestry and faculty — which the authors characterise as nearly 60% reduced odds [s2].

Students reporting worse sleep also more often reported a drop in grades than those reporting no change, 59% versus 38% (P=0·015) [s2].

What that association can and cannot mean

A 3% response rate to an open online survey is the central caveat, and it points in a predictable direction: students most affected by outages have the strongest reason to respond, and the sample is 72% female against a general student population that is unlikely to be. Everything measured is self-reported, including both the sleep change and the grade change, which means recall and attribution are entangled — a student whose grades fell has a ready explanation available.

The backup-power association is the most robust part, because it compares two groups within the same survey under the same conditions and survives adjustment for several plausible confounders [s2]. But access to alternative power tracks household income, and income tracks a great deal else. The adjustment set does not include a direct measure of it.

The authors' conclusion is correspondingly measured: that loadshedding is associated with poorer self-reported sleep, studying habits and grades, and may be linked to increased risk of mental and physical health problems, so mitigation is needed [s2].

Why both papers matter more than their individual findings

Neither study is definitive. A cross-sectional national survey and a single-university online questionnaire are the kind of work that establishes what questions are worth asking, not what the answers are.

Their value is in the questions they surface that the existing literature does not contain. Sleep regularity as the dimension in shortest supply, rather than duration [s1]. Electricity reliability as a sleep exposure [s2]. Urban residence associating with better rather than worse sleep [s1]. None of these would be predicted from a field built almost entirely on North American and European samples, and none can be addressed by interventions designed for those settings.

Sources

• Beyond sleep duration: Assessment of multidimensional sleep health in a nationally recruited sample of Nigerian adults, Sleep Health, 5 May 2026
• Hello darkness, my old friend: Electricity loadshedding effects on sleep and studying habits in South African university students, Sleep Health, 22 August 2026