Substrate ·evidence-based
interventions / Vitamin D / sleep

Does Vitamin D help sleep? (Grade C evidence)

For sleep, Vitamin D sits at Grade C — a hint of benefit in limited trials, especially in adults, low certainty, at doses varies across trials.

Exact question reviewed

Population
adults
Intervention
Vitamin D · varies across trials
Comparator
not reported
Outcome
sleep
Time horizon
not reported

Bottom line. For sleep, Vitamin D sits at Grade C — a hint of benefit in limited trials, especially in adults, low certainty, at doses varies across trials. [1 RCT]

Direction
benefit
Magnitude
Systematic review and meta-analysis (moderate certainty): vitamin D supplementation showed promise for improving sleep quality, but its effect on sleep quantity, sleep disorders, sleepiness, and restless legs syndrome was inconsistent across studies. Promising but not settled.
Grade
C
Certainty
low
Clinical meaning
small but potentially useful
Who it applies to
adults
Dose / form studied
varies across trials
Safety
not assessed
The one limitation
Claim-specific limitation details are not available in this public record.

Reviewed · Evidence last changed · Claim clm_ec_b8-vitd-sleep v0

Grade
C
what does the grade mean?
Certainty
low
what does certainty mean?

Grade C / low: hints of benefit in small trials; a well-run RCT could easily push this to B or to null.

Who it works for

Best-studied in adults. Recorded studied dose: varies across trials.

Evidence

StudyDesignRoleCite
Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies.peer-reviewedsupportsPMID:35268051

Why this grade

Reasoning trace

The current record stores Grade C at low certainty and links 1 publishable source. A claim-specific domain-by-domain grading rationale is not available in this public record, so no reason for upgrading or downgrading is inferred here.

Audit and version

Claim ID
ec_b8-vitd-sleep
Claim version
not reported
Governance
legacy, not verified
Last evidence search
not reported
Last editorial review
2026-07-16T16:40:39.059Z

Public receipt · Machine-readable claim · Methodology

Dose & form

Studied intake: varies across trials.

How it stacks up for sleep

Grade history

No grade changes yet. Initial grade assigned; re-reviewed on every 6 months (Grade C+) — next review by . Methodology v1.

Re-review cadence: every 6 months (Grade C+) · next scheduled by · methodology v1.

Frequently asked

How long does Vitamin D take to work for sleep?

Trials of Vitamin D for sleep typically report effects within 2–4 weeks, though individual response varies. Studies rarely find benefit inside 1 week for chronic outcomes.

What dose was used in studies of Vitamin D for sleep?

Studied doses for Vitamin D in sleep trials cluster around varies across trials. See the dose block for the specific range and how it varies by form.

Does Vitamin D work for sleep if I'm not deficient?

The effect concentrates in adults. If your baseline is normal, expect a smaller effect than the trial averages.

Vitamin D or the next-best alternative for sleep?

See the compare block above for the head-to-head with the most-cited alternative. Grade + certainty differences matter more than any single trial.

Related

What this is — and is not

Evidence description
Systematic review and meta-analysis (moderate certainty): vitamin D supplementation showed promise for improving sleep quality, but its effect on sleep quantity, sleep disorders, sleepiness, and restless legs syndrome was inconsistent across studies. Promising but not settled.
Substrate's interpretation
The current reviewed record assigns Grade C at low certainty. A domain-by-domain rationale is shown only when recorded.
Discuss with a clinician
If you're on medication or have a condition that changes the calculus, bring the interaction & population blocks above to your pharmacist or prescriber before deciding.
Individualized medical advice
Not provided here or on any Substrate surface (API, agent tool, embed) — see YMYL policy.

Cite this page

Citation is encouraged. The proposed reuse license is CC-BY-4.0; status: pending-governance-ratification.

Plain-text citation
Substrate. Does Vitamin D help sleep? (Grade C). https://evidencebased.info/interventions/vitamin-d/sleep. Updated 2026-07-16.
BibTeX
@misc{substrate_entionsvitamindsleep,
  author = {Substrate editorial},
  title  = {Does Vitamin D help sleep?},
  year   = {2026},
  url    = {https://evidencebased.info/interventions/vitamin-d/sleep},
  note   = {Grade C, evidencebased.info}
}

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