PER3 rs1144566: Understanding Your Circadian Rhythm Variant
The rs1144566 variant is a missense coding change located within the PER3 gene, which plays a central role in the human circadian clock. Research suggests this variant may be associated with individual differences in diurnal preference and sleep phase architecture.
What each genotype means
Typical circadian baseline
You carry two copies of the common C allele for this PER3 variant. Research in European cohorts suggests this baseline genotype is not linked with shifts in diurnal preference or sleep phase architecture. Because overall chronotype is influenced by dozens of genes and environmental light exposure, this genotype reflects a standard baseline profile.
Carried by approximately 84% to 86% of individuals of European descent and represents the predominant genotype worldwide.
Modulated diurnal preference
You carry one copy of the minor G allele, corresponding to the p.Pro415Ala missense change in the PER3 clock protein. Population studies, including large UK Biobank analyses, have observed limited associations between this variant and subtle modulations in diurnal preference or circadian phase timing. However, its overall individual effect on sleep timing is modest and subject to broader lifestyle and polygenic factors.
Found in approximately 14% to 15% of European populations, with lower frequencies observed in East Asian cohorts.
Altered sleep phase tendency
You carry two copies of the minor G allele in the PER3 gene. Homozygosity for this amino-acid alteration has been evaluated in circadian rhythm research for potential associations with shifted sleep-wake schedules, though verified evidence remains limited. Circadian traits are complex, and daily light cues alongside sleep hygiene generally exert a much stronger influence than this single variant alone.
Carried by fewer than 1% of individuals across most global populations.
What is the rs1144566 Variant?
The rs1144566 variant is a single nucleotide polymorphism (SNP) located in the PER3 gene. In genetic terms, this is a missense mutation, meaning the change in the DNA sequence results in a different amino acid being incorporated into the resulting protein—specifically, a proline to alanine substitution at position 415 (p.Pro415Ala). This variant is situated within the coding region of the gene, which provides the instructions for building the PER3 protein. Because this protein is a key component of the molecular machinery that regulates our internal biological clock, researchers are interested in how such structural changes might influence the timing and quality of sleep. It is important to note that while this variant is cataloged as a trait-associated SNP, it is just one of many genetic factors that contribute to the complex, polygenic nature of human sleep patterns.
The Role of the PER3 Gene
The PER3 gene encodes the Period Circadian Regulator 3 protein. This protein is part of a feedback loop that generates rhythmic oscillations in gene expression, which in turn drive the circadian rhythms observed in nearly all human tissues. These rhythms are essential for coordinating physiological processes, such as the sleep-wake cycle, hormone secretion, and body temperature regulation, with the 24-hour solar day. PER3 is particularly noted for its role in sleep homeostasis—the process that builds up 'sleep pressure' the longer we stay awake. Studies have shown that variations in PER3 can influence how individuals respond to sleep deprivation and how they recover from it. By modulating the expression of genes involved in neural network plasticity and sleep regulation, PER3 helps determine the timing of our internal clock and our susceptibility to circadian misalignment.
Research and Evidence Strength
The association between PER3 variants and sleep-related traits is a subject of ongoing scientific investigation. While the PER3 gene is widely recognized as a critical clock component, the evidence linking the specific rs1144566 variant to clinical outcomes is currently considered limited. Much of the existing research on PER3 focuses on a different type of variation—a variable number tandem repeat (VNTR)—which has been more extensively studied in relation to delayed sleep phase syndrome and diurnal preference. Because rs1144566 is a missense variant, its functional impact may differ from the length-based polymorphisms often cited in literature. Current findings in the GWAS Catalog and other databases indicate that while there is interest in this SNP, it has not been definitively linked to a specific medical condition. As with many complex traits, sleep patterns are influenced by a combination of genetic, environmental, and lifestyle factors, making it difficult to isolate the effect of a single SNP.
What You Can and Cannot Do With This Information
Understanding your genetic variants can be an interesting way to learn about your biological predispositions, but it is essential to maintain a balanced perspective. You cannot use this information to diagnose a sleep disorder or to predict your exact sleep schedule. Sleep is a highly complex behavior influenced by your environment, stress levels, diet, and overall health. If you are experiencing persistent sleep issues, such as difficulty falling asleep, staying asleep, or excessive daytime sleepiness, you should consult a healthcare professional or a sleep specialist. They can provide a comprehensive evaluation that goes far beyond genetic testing. Furthermore, if you are considering any changes to your sleep hygiene or if you are taking medications that affect your sleep-wake cycle, always discuss these with your clinician or pharmacist. Genetic data should be viewed as a small piece of a much larger puzzle regarding your health.
How common is this variant?
The minor allele frequency for rs1144566 is approximately 0.08 in European populations. The variant is present globally, though frequencies may vary across different ancestral groups.
Frequently asked questions
Does having the rs1144566 variant mean I have a sleep disorder?
No. Genetic variants like rs1144566 are associated with natural variations in sleep traits, not necessarily with clinical sleep disorders. Sleep disorders are complex conditions diagnosed by medical professionals based on symptoms and clinical testing.
Can I change my sleep habits based on my PER3 genotype?
While your genetics may influence your natural chronotype, you should not make significant changes to your health or sleep routine based on a single SNP. Always consult with a healthcare provider before making changes to your lifestyle or sleep management plan.
Is rs1144566 the same as the PER3 VNTR polymorphism?
No. The rs1144566 variant is a single nucleotide change (a missense variant), whereas the PER3 VNTR is a length-based polymorphism involving a repeating sequence of DNA. They are distinct types of genetic variation within the same gene.
Where can I find more information about my sleep genetics?
You can explore resources like MedlinePlus Genetics or the GWAS Catalog for general information on how genes influence sleep. For personal health concerns, your primary care physician or a sleep specialist is the best source of information.
Sources & further reading
Educational information only, last refreshed 10/18/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This SNP is associated with chronotype scores in older adults, suggesting a role in circadian regulation.
This SNP is associated with average delta power during sleep, a marker of sleep intensity.
Missense variant P415A in PER3 associated with familial advanced sleep phase syndrome and circadian phase preference.
Common synonymous variant in PER3 tightly linked with circadian diurnal preference and morningness-eveningness tendencies.
Promoter/intronic variant of PER3 tagging circadian phase angle, diurnal preference, and homeostatic sleep pressure response to sleep loss.
Part of a well-characterized functional haplotype in PER3 influencing individual diurnal preference and susceptibility to delayed sleep phase syndrome.