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Randomized trial · measured the question itself

Trial in 139 adults after hip replacement: more sleep on day 2, similar sleepiness

Haider and colleagues · The Journal of arthroplasty · 2025

Original title: Does Melatonin Improve Sleep Following Primary Total Hip Arthroplasty? A Randomized, Double-Blind, Placebo-Controlled Trial.

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What the study found

Mixed

Sleepiness scores were similar (melatonin: 6.0 ± 4.0; placebo: 6.8 ± 4.5, P = 0.35). Melatonin users slept more on day 2 (6.5 ± 1.7; 5.7 ± 2.4, P = 0.017) and had lower sleep disturbance scores (52.5 ± 9.3; 56.3 ± 9.2, P = 0.040).

The study at a glance

Type of study
Randomized trial
Who or what was studied
139 people · adults after hip replacement surgery
What was tested
Melatonin 5 mg each night vs placebo for 14 days
What it measured
The question itself: sleep, and safety with long-term use
Daily amount
5 mg a day
How long
2 weeks
Who has a stake
No disclosure in PubMed
No disclosure in PubMed.
Journal
The Journal of arthroplasty, 2025
Source
PubMed record 40383169. This page is based on the abstract only.

How much this study counts

  • ✓Randomized: people were put into groups by chance, so the groups start out alike.
  • ✓Compared with a placebo, a dummy treatment.
  • •Medium size: 139 people.
  • –Short: 2 weeks. Longer-term effects are unknown.
  • ✓Measured the question itself: sleep, and safety with long-term use.
  • •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: sleep onset and sleep quality

    8

    2 benefit, 2 mixed, 4 no difference

    ↑ This study is the ringed dot

  2. Trials in people: other measures

    2

    1 benefit, 1 no difference

  3. Trials in people: lab tests or safety

    0

    None among the papers we read.

  4. Population studies

    0

    None among the papers we read.

  5. Blood levels and genes

    0

    None among the papers we read.

↓ Weaker evidence

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

How it fits with the other research

The short answer to “Does melatonin help you sleep?”

A small effect, clearer in children.

Confidence: low. Based on 20 on-topic papers.

Read the full answer

Of the other 7 papers on the same step: 2 benefit, 1 mixed, 4 no difference. This one found mixed. It differs from most of them.

Other papers on the same step

See all 20 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 differed. The reviewer checked the abstract and kept the first read. 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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