We searched the literature from inception to December 31st, 2022 in three main databases, PubMed, Web of Science, and Embase, to identify systematic reviews on the association between sleep duration and hypertension. To minimize the risk of missing the eligible article, we also screened references of all included studies and related citations in PubMed to identify additional publications. This study was registered with the PROSPERO registry: CRD42023459901 and can be viewed at http://www.crd.york.ac.uk/prospero.

Studies that satisfied the below criteria were eligible: (1) were published in a peer-reviewed journal in English; (2) a systematic review assessed the associations between sleep duration and hypertension. The exclusion criteria were as follows: (1) lacked sufficient information; (2) were not published as full research articles, such as comments or letters; (3) were studied with the same data from the same authors.

The terminology used in the search included: (“short sleep duration” OR “long sleep duration” OR “sleep duration” OR “sleep hours”) AND (“hypertension” OR “blood pressure” OR “high blood pressure”) AND (“systematic review” OR “review” OR ‘meta-analysis”). Detailed search strategies are listed in Supplementary 1.

Two investigators (Y.QL and X.HD) assessed the eligibility of each study independently. Titles and abstracts were screened for potentially relevant articles, and then full-text screening was completed independently, in which, a 10% random sample of articles was assessed for accuracy. All disagreements were discussed among those two reviewers, with any inconsistent comment was resolved by an independent third reviewer (Z.ZQ).

A standardized form was designed for data extraction of items of interest from the included SRs. Basic characteristics and findings relating to the SRs that were reviewed and extracted by reviewers. The basic characteristics extracted from the SRs were the following: year of publication, study design, sample size, sleep duration, estimates, and other details of adherence of SRs to individual items included in AMSTAR-2 or 2020 PRISMA guidelines.

AMSTAR guidelines were used to assess the methodological quality of the included SRs. The AMSTAR-2, a new and improved version of AMSTAR, was considered a reliable and valid tool for evaluating the reporting quality of SRs [15]. AMSTAR-2 assessed the quality of SRs using 16 items which concern the following aspects: including the components of PICO, a priori design, study design and data extraction in duplicate, comprehensive literature search, a list of included and excluded studies, and the criteria of inclusion and exclusion, bias assessment, reporting the sources of funding, using appropriate methods for statistical combination of results, assessment of the likelihood of publication bias, and assessment of the potential conflicts of interest. The items are answered with a “yes,” “partial yes,” “no,” and “not applicable.” In this study, four categories were divided according to the answers of each SR: “high quality”, refers to the SR with no or one non-critical weakness, which means the systematic review could provide an accurate and comprehensive summary of the study question using the results of the available studies; “moderate quality”, refers to the SR with more than one non-critical weakness, which means the SR may provide an accurate summary based on the results of the available studies; “low quality”, refers to the SR with one critical flaw with or without non-critical weaknesses, which means that the review had a critical flaw and may not provide an accurate and comprehensive summary using the available studies; “critically low” refers to the SR with more than one critical flaw with or without non-critical weaknesses, which means the SR should not be reliable to provide an accurate and comprehensive summary for the study question.

PRISMA checklist was used to evaluate the reporting quality of SRs. The 2020 PRISMA checklist, which is the evidence-based minimum set of items for reporting in SRs and MAs, uses 27 items to check the quality of SRs in seven aspects: title, abstract, introduction, methods, results, discussion, and other information including protocol, support, competing interests, data and code used in analyses. The detailed items of these two guidelines are listed in Supplementary 2.

Three reviewers (Z.ZQ, Y.QL, and X.HD) independently evaluated the methodological quality of these SRs using the 2020 PRISMA checklist and AMSTAR-2. The agreement proportion and Cohen’s kappa value (k) for each of the items of AMSTAR-2 were calculated. Good agreement was obtained in this study (k = 0.71) between the two reviewers.