How We Rate Products
Our evidence rating system cuts through marketing claims. Here's exactly how we evaluate sleep products.
The Evidence Rating System
Every product receives an evidence rating from A to D. This rating reflects the quality and quantity of scientific research supporting the product's claims—not user reviews, not popularity, not price.
A Rating: Strong Evidence
The gold standard
Criteria:
- Multiple peer-reviewed studies (3+) with consistent positive results
- Randomized controlled trials (RCTs) or systematic reviews
- Studies published in reputable journals
- Adequate sample sizes and proper methodology
- Effects replicated by independent research teams
Examples: Temperature regulation for sleep, blue light blocking (true blocking, not filtering), magnesium for sleep quality, white noise for sleep onset
B Rating: Moderate Evidence
Promising but incomplete
Criteria:
- 1-2 peer-reviewed studies with positive results
- Studies may have limitations (small sample, short duration)
- Mechanism of action is scientifically plausible
- May include well-designed observational studies
- More research needed to confirm findings
Examples: Sleep tracking accuracy, L-theanine for relaxation, weighted blankets for anxiety, tart cherry for natural melatonin
C Rating: Limited Evidence
Mostly anecdotal
Criteria:
- Primarily anecdotal evidence or user testimonials
- Very limited or preliminary research
- Studies have significant methodological issues
- Mechanism is plausible but unproven
- Mixed or inconsistent results across studies
Examples: Apigenin for sleep, many herbal supplements, grounding/earthing products, certain sleep tracking features
D Rating: No Evidence
Marketing claims only
Criteria:
- No peer-reviewed research supporting claims
- Claims based purely on marketing or theory
- Research contradicts the claimed benefits
- Mechanism of action is implausible
- "Studies" are industry-funded with no peer review
Examples: Clear "blue light filtering" glasses for sleep, oral GABA supplements (don't cross blood-brain barrier), most underdosed "sleep blend" supplements
Our Research Process
Identify Claims
We start by cataloging every claim a product makes. "Improves deep sleep." "Reduces sleep onset time." "Clinically proven." Each claim becomes a research question.
Literature Review
We search PubMed, Google Scholar, and other databases for peer-reviewed research. We prioritize systematic reviews, meta-analyses, and randomized controlled trials. We also review the cited studies in product marketing.
Evaluate Study Quality
Not all studies are equal. We assess sample size, methodology, conflict of interest, publication venue, and whether results have been replicated. Industry-funded studies without independent replication are flagged.
Assign Evidence Rating
Based on the totality of evidence, we assign an A through D rating. This rating reflects our confidence that the product does what it claims, based on current scientific understanding.
Evaluate Practicality
Beyond evidence, we consider price, usability, subscription requirements, build quality, and real-world factors. A product can have great evidence but still be impractical for most people.
Ongoing Updates
Science evolves. We revisit ratings when significant new research emerges. All pages display their last update date so you know how current the information is.
Star Ratings vs. Evidence Ratings
You'll notice products have two ratings: stars and evidence letters. They measure different things.
⭐ Star Rating (1-5)
Reflects overall product quality, value, and user experience. Considers build quality, ease of use, customer support, price-to-value ratio, and user satisfaction. A product can be excellent at what it does even if scientific evidence is limited.
A Evidence Rating (A-D)
Reflects scientific evidence supporting the product's claimed benefits. A high-quality product with no research backing still gets a D evidence rating. This is purely about what the science says.
Example: A well-made, comfortable weighted blanket might get 4.5 stars (great product) but a C evidence rating (limited research on sleep benefits). Both ratings are accurate—they just measure different things.
Editorial Independence
Our recommendations are not for sale. Period.
What we commit to:
- Evidence ratings are never influenced by affiliate relationships
- Companies cannot pay for better ratings or featured placement
- "Editor's Choice" picks are based on merit, not commissions
- We disclose all affiliate relationships clearly
- Negative reviews are published when warranted
What we won't do:
- Accept payment for positive reviews
- Hide product flaws or subscription requirements
- Recommend products we wouldn't use ourselves
- Inflate evidence ratings for affiliate products
- Remove negative information at a company's request
Affiliate Disclosure
SleepZone HQ participates in affiliate programs. When you click a product link and make a purchase, we may earn a commission at no additional cost to you.
This is how we fund our research and keep the site running. However, affiliate relationships never influence our ratings, recommendations, or editorial content.
We often recommend products with lower commissions over higher-commission alternatives when they better serve your needs. Our credibility is worth more than any single commission.
Limitations & Caveats
We're not doctors
Our content is educational, not medical advice. Sleep disorders like insomnia, sleep apnea, and restless leg syndrome require professional diagnosis and treatment. Products can help, but they're not substitutes for healthcare.
Science changes
Research evolves. A product rated C today might earn an A if new studies emerge. We update ratings as evidence changes, but we can't guarantee real-time accuracy. Check the "last updated" date on each page.
Individual variation
What works for most people might not work for you. Even A-rated interventions don't help everyone. Our ratings reflect population-level evidence, not guarantees of individual results.
We don't test everything
We rely primarily on published research and user reports, not hands-on testing of every product. When we have direct experience with a product, we note it. Otherwise, our assessments are research-based.
Questions about our methodology?
We're always open to feedback and corrections.