PER3 rs11974967: Understanding Your Genetic Sleep Associations
The rs11974967 variant is a common genetic marker located within the PER3 gene, which plays a key role in regulating the body's internal clock. It is primarily studied for its association with individual differences in sleep timing, homeostatic sleep pressure, and cognitive performance following sleep deprivation.
What each genotype means
Typical sleep pressure and resilience
You carry two copies of the C allele at rs11974967, which is in tight linkage disequilibrium with the shorter 4-repeat allele of the PER3 variable number tandem repeat (VNTR) polymorphism. Studies suggest this baseline pattern is associated with slightly greater resilience to acute sleep deprivation and lower baseline slow-wave sleep pressure compared to carriers of the longer repeat. Because diurnal preference and cognitive stamina are polygenic, overall circadian timing is influenced by many other genetic and environmental factors.
Carried by roughly 35% to 50% of individuals in European populations, representing the most common genotype.
Intermediate circadian and sleep profile
You carry one copy of the C allele and one copy of the T allele at rs11974967, functioning as a tag for the heterozygous 4/5-repeat PER3 VNTR state. Research suggests individuals with this intermediate genotype tend to fall between the two homozygotes in their homeostatic sleep drive and physiological response to extended wakefulness. These findings represent subtle population-level averages rather than deterministic traits or sleep disorder diagnoses.
Carried by approximately 40% to 50% of individuals in European populations.
Increased vulnerability to sleep loss
You carry two copies of the T allele at rs11974967, which strongly tags the longer 5-repeat allele of the PER3 VNTR polymorphism. Published research links this genotype with higher homeostatic sleep pressure, a tendency toward a morning chronotype, and greater cognitive vulnerability or decrements during acute sleep loss. However, evidence remains limited and these associations represent modest statistical tendencies that do not replace clinical sleep evaluation.
Carried by approximately 8% to 15% of individuals of European ancestry and is generally less common in other global populations.
What is the rs11974967 Variant?
The rs11974967 variant is a single-nucleotide polymorphism (SNP) situated within the PER3 gene. In the context of human genetics, this variant is often discussed as a 'tag' or proxy marker. This means that while rs11974967 itself is a specific change in the DNA sequence, it is frequently inherited alongside a well-known, primate-specific variable-number tandem-repeat (VNTR) polymorphism located in the coding region of the same gene. Because these two genetic features are in strong linkage disequilibrium—meaning they are typically passed down together from parents to offspring—researchers use rs11974967 to study the functional effects of the PER3 gene. By identifying this SNP, scientists can better understand how variations in the PER3 gene might influence biological processes related to rest and activity cycles.
The Role of the PER3 Gene
The PER3 gene, or Period Circadian Regulator 3, is a core component of the molecular machinery that governs circadian rhythms in humans and other mammals. These rhythms are the internal biological processes that follow a roughly 24-hour cycle, influencing everything from hormone release to body temperature and sleep-wake patterns. While many clock genes are involved in maintaining the timing of these cycles, PER3 is particularly noted for its involvement in sleep homeostasis. Sleep homeostasis refers to the 'sleep drive' or the pressure to sleep that builds up the longer an individual stays awake. Research suggests that PER3 helps regulate how the brain responds to sleep loss and how it manages the intensity of sleep, such as the amount of slow-wave activity observed during deep sleep stages.
Research Associations and Evidence Strength
Scientific research has linked variations in the PER3 gene to several sleep-related traits, including diurnal preference (whether someone is a 'morning lark' or 'night owl') and cognitive vulnerability to sleep deprivation. Studies have observed that individuals with certain PER3 genotypes may experience more significant declines in cognitive performance when they do not get enough sleep compared to others. However, it is important to note that the evidence for these associations is considered limited. While some studies have shown clear differences in EEG markers of sleep homeostasis, other findings have been inconsistent or difficult to replicate across different populations. Furthermore, these associations do not imply a direct cause-and-effect relationship for any individual. Sleep is a complex trait influenced by a vast array of genetic, environmental, and lifestyle factors, and the PER3 variant is only one small piece of a much larger puzzle.
Population Frequency
The rs11974967 variant is considered a common genetic marker. Across European populations, the minor allele frequency is typically observed to be between 0.30 and 0.40. This means that a significant portion of the population carries at least one copy of the variant allele. Because it is common, it is not considered a rare mutation or a disease-causing variant in the traditional sense. Instead, it represents a normal range of genetic diversity that contributes to the natural variation in human sleep patterns. Frequency can vary by ancestry, and researchers continue to study how these patterns manifest across diverse global populations to better understand the evolutionary history and functional impact of the PER3 gene.
Interpreting Your Genetic Information
If you have access to your genetic data regarding rs11974967, it is important to view this information as a tool for general education rather than a medical diagnostic. Because the associations between this variant and sleep traits are based on statistical trends in large groups, they cannot predict your personal sleep needs or your specific response to sleep loss. You cannot use this information to diagnose a sleep disorder or to determine your 'chronotype' with certainty. If you are concerned about your sleep quality, daytime fatigue, or cognitive performance, the most effective approach is to consult with a healthcare professional or a sleep specialist. They can provide personalized guidance based on your clinical history and symptoms, which are far more informative than any single genetic variant.
How common is this variant?
The rs11974967 variant is common, with a minor allele frequency of approximately 0.30 to 0.40 across European populations.
Frequently asked questions
Does this variant mean I have a sleep disorder?
No. This variant is a common genetic marker associated with natural variations in sleep patterns, not a diagnostic indicator for sleep disorders. If you are experiencing persistent sleep issues, please consult a medical professional.
Can I use this to change my sleep schedule?
Genetic variants like rs11974967 do not dictate your ability to change your sleep habits. Lifestyle factors, such as light exposure and consistent routines, play a much larger role in managing your sleep-wake cycle.
Is this variant linked to my risk of disease?
Current research focuses on sleep homeostasis and cognitive performance rather than disease risk. There is no evidence to suggest this variant is a primary cause of any specific medical condition.
Why do studies show different results for this gene?
Sleep is a complex trait influenced by many genes and environmental factors. Differences in study design, sample size, and the populations being studied often lead to varying results in genetic research.
Sources & further reading
Educational information only, last refreshed 10/17/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs11974967?
Upload a raw DNA file from 23andMe, AncestryDNA, MyHeritage, or FamilyTreeDNA and see this variant — plus thousands more — interpreted in your full report.
Get my report — $29Related variants in PER3
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.
Common synonymous variant in PER3 tightly linked with circadian diurnal preference and morningness-eveningness tendencies.
Missense variant P415A in PER3 associated with familial advanced sleep phase syndrome and circadian phase preference.
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.