---
title: "Systematic review of light exposure impact on human circadian…"
description: "Even low levels of various light types, especially blue and violet light, can rapidly disrupt human circadian rhythms and melatonin production, informing…"
url: "https://magellanlongevity.com/study/bluelight.md"
canonical: "https://magellanlongevity.com/study/bluelight.html"
html: "https://magellanlongevity.com/study/bluelight.html"
type: "study"
study_key: "bluelight"
journal: "Chronobiology International"
year: 2019
pmid: "30311830"
doi: "10.1080/07420528.2018.1527773"
citations: 1
updated: 2026-09-02
author: "Gabriel Radu, DO"
author_credentials: "Physiatrist (PM&R). NY medical license 275110. NPI 1376861765."
publisher: "Magellan Longevity"
content_format: "markdown"
---

# Systematic review of light exposure impact on human circadian rhythm.

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## Citation

| Field | Value |
| --- | --- |
| Journal | Chronobiology International |
| Year | 2019 |
| PMID | [30311830](https://pubmed.ncbi.nlm.nih.gov/30311830/) |
| DOI | [10.1080/07420528.2018.1527773](https://doi.org/10.1080/07420528.2018.1527773) |
| Study key | bluelight |

## Takeaway

Even low levels of various light types, especially blue and violet light, can rapidly disrupt human circadian rhythms and melatonin production, informing future light pollution assessments.

## The question

What is the impact of light exposure on human circadian rhythm, and how can this information be used to develop an evaluation method for light pollution in life cycle assessment (LCA)?

## Hypothesis

Mistimed light exposure disrupts the human circadian rhythm, potentially leading to health impacts, and a systematic review is needed to synthesize existing research to inform light pollution evaluation in LCA.

## Methods

A systematic literature search was conducted using the concepts 'light' and 'circadian rhythm,' with additional terms 'melatonin' and 'rapid-eye-movement (REM) sleep.' The search yielded 128 articles. Data was collected and analyzed from these articles, with a focus on melatonin secretion (122 articles) and REM sleep (13 articles). Studies were categorized by light exposure type (specific vs. prevailing conditions). Quality criteria for further synthesis included a minimum sample size of 20 subjects and detailed light exposure information (spectrum/wavelength, illuminance/irradiance/photon density). This resulted in 13 qualified studies on melatonin and 2 on REM sleep for further analysis.

## Results

A two-hour exposure to blue light (460 nm) in the evening suppressed melatonin, with the maximum suppression occurring at the shortest wavelengths (424 nm, violet). Melatonin concentration recovered within 15 minutes after light cessation. Melatonin secretion and suppression decreased with age, but light-induced circadian phase advance was not impaired by age. Light exposure in the evening, at night, and in the morning affected the circadian phase of melatonin levels. Even long wavelengths (631 nm, red) and intermittent light exposures induced circadian resetting, and low light levels (5-10 lux) at night with eyes closed also induced a circadian response.

## Conclusion

Light exposure significantly impacts human circadian rhythm, with blue and violet light being particularly effective at suppressing melatonin. The effects are rapid and can occur even with long wavelengths, intermittent exposure, and low light levels during sleep. This review provides a basis for developing an evaluation method for light pollution in life cycle assessment concerning human circadian impacts.

## Limitations

Many studies had small sample sizes (39 out of 128 studies had 10 or fewer subjects). The review focused primarily on adults in their twenties or thirties, with very few studies on children and elderly adults. The variety of methods used in individual experimental studies, including definitions of light exposure and outcomes, posed a challenge for synthesis.

## Verbatim from the abstract

> Findings suggest that mistimed light exposure, including evening blue-enriched light, disrupts the human circadian rhythm and melatonin signalling.

## Where this study is used on Magellan

This paper is one of the citations behind the evidence grade on the pages below. Grades are assigned from the published research and are independent of affiliate commissions.

| Compound or device | Evidence grade | Graded pages |
| --- | --- | --- |
| Sleep Optimization & Circadian Systems | — | — |
| Blue-Light Management & Circadian Lighting | Tested — did not work | [SYB Clear Blue Light Glasses](https://magellanlongevity.com/p/58.md) |

## Reference

1. **Systematic review of light exposure impact on human circadian rhythm.**
   Chronobiology International 2019 · [PMID 30311830](https://pubmed.ncbi.nlm.nih.gov/30311830/) · [DOI 10.1080/07420528.2018.1527773](https://doi.org/10.1080/07420528.2018.1527773)

   > Findings suggest that mistimed light exposure, including evening blue-enriched light, disrupts the human circadian rhythm and melatonin signalling.

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## Related on Magellan Longevity

- [SYB Clear Blue Light Glasses](https://magellanlongevity.com/p/58.md) — product graded on this and related evidence
- [Sleep duration and risk of all-cause mortality: a systematic review and meta-analysis.](https://magellanlongevity.com/study/sleep_mortality.md)
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- [Evidence-based longevity supplements](https://magellanlongevity.com/longevity-supplements.md)

## Scope and disclosures

Educational information, not medical advice. Nothing here is intended to diagnose, treat, cure, or prevent any disease. Talk to your physician before starting any supplement or device, especially if you are pregnant, nursing, or taking medication.

Editorial firewall: evidence grades are assigned from the published research and are independent of any affiliate commission. As an Amazon Associate, Magellan Longevity earns from qualifying purchases.

Reviewed for accuracy by a board-certified physician (DO).