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Population study: followed a group

Study that followed 461,347 adults: short and long sleep linked to more heart attacks

Daghlas and colleagues · Journal of the American College of Cardiology · 2019

Original title: Sleep Duration and Myocardial Infarction.

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What the study found

Mixed

Compared with 6 to 9 h, short sleepers had a 20% higher heart attack risk (HR: 1.20; 95% CI: 1.07 to 1.33) and long sleepers 34% higher (HR: 1.34; 95% CI: 1.13 to 1.58). Genetic analysis fit a causal effect of short sleep.

The study at a glance

Type of study
Population study: followed a group
Who or what was studied
461,347 people · UK Biobank adults free of heart disease, plus genetic data
What was tested
Short (under 6 h) and long (over 9 h) sleep vs 6 to 9 h, then heart attacks
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
Journal of the American College of Cardiology, 2019
Source
PubMed record 31488267. This page is based on the abstract only.

How much this study counts

  • –Shows a link, not a cause: people chose their own habits, and other differences between them may explain the result.
  • ✓Followed people over time, so habits were recorded before the outcome happened.
  • ✓Large: 461,347 people.
  • ✓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

Each dot is one on-topic paper on this question. Steps near the top answer the question more directly.

↑ 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

    ↑ This study is the ringed dot

  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

Of the other 10 papers on the same step: 5 benefit, 3 mixed, 2 no difference. This one found mixed.

Other papers on the same step

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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