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Pooled review (meta-analysis)

Pooled review of 137 studies: long sleep linked to higher death and heart risk

Jike and colleagues · Sleep medicine reviews · 2018

Original title: Long sleep duration and health outcomes: A systematic review, meta-analysis and meta-regression.

Under review. A person has not yet checked this summary against the paper. It is written from the PubMed abstract. Until a person checks it, search engines are asked not to list this page.

What the study found

Points to harm

Long sleep was linked to higher risk of death (RR, 1.39; 95% CI, 1.31-1.47), diabetes (1.26), heart disease (1.25), stroke (1.46) and obesity (1.08). It was not linked to high blood pressure (1.01).

The study at a glance

Type of study
Pooled review (meta-analysis)
Who or what was studied
137 studies, 5,134,036 people · adults in 137 long-term follow-up studies
What was tested
Long sleepers compared with normal sleepers
What it measured
The question itself: death, heart disease and other health outcomes
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
Sleep medicine reviews, 2018
Source
PubMed record 28890167. This page is based on the abstract only.

How much this study counts

  • ✓Pools the results of 137 studies with 5,134,036 people.
  • •A pooled review is only as strong as the studies it pools.
  • ✓Measured the question itself: death, heart disease and other health outcomes.
  • •The PubMed record has no conflict-of-interest statement.
  • •Summarized from the PubMed abstract only. The full paper may hold details the abstract leaves out.

✓ Strength– Limit• Note

These points come from fixed rules about the type of study, its size and length, what it measured, and who has a stake. Every study on Digestery gets the same rules.

Where this study sits

This paper is not on the ladder. It is a pooled review (meta-analysis), and reviews and opinion pieces discuss studies that are already counted on the steps below.

↑ Stronger evidence

  1. Trials in people: death and chronic disease

    0

    Not done yet. This is the step that would answer the question.

  2. Trials in people: other measures

    1

    1 benefit

  3. Trials in people: lab tests or safety

    0

    None among the papers we read.

  4. Population studies

    11

    5 benefit, 4 mixed, 2 no difference

  5. Blood levels and genes

    1

    1 benefit

↓ Weaker evidence

  • Points to benefit
  • Mixed
  • No difference
  • No direction
  • Points to harm

How it fits with the other research

The short answer to “How much sleep do adults need for good health?”

Lowest risk at about 7 hours.

Confidence: low. Based on 22 on-topic papers.

Read the full answer
  • Quoted in “What we found”: Across 137 studies of 5,134,036 people, long sleepers had 1.39 times the death risk of normal sleepers, and higher stroke (1.46) and diabetes (1.26) risk.
  • Part of the finding “Diabetes and weight follow similar patterns”.
  • Summed up in “What reviews found”: Pooled 137 studies with 5,134,036 people. Long sleep was linked to higher risk of death (RR 1.39), diabetes, heart disease, stroke and obesity, but not high blood pressure. Authors ask whether the link is causal.
  • Marked as a key paper in the research timeline: Companion pooled review links long sleep too.
  • Open item for a person: Itani 2017 and Jike 2018 are companion meta-analyses; they and umbrella review Li 2022 likely share cohorts. Check overlap.

Other reviews on this question

See all 22 studies on this question

How this page was made

Label

First read of the abstract
Claude Sonnet
Independent second read
Claude Haiku
Differences settled
The two reads agreed on every checked field. Claude Opus 5.5.
Headline
Claude Sonnet, from the checked study record. A script checked its numbers and wording.
Numbers
Checked against the abstract by a script
“How much this study counts”
Fixed rules, the same for every study
Source check by a person
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