CLOCK rs1801269: What Your Genotype Means
The rs1801269 variant is a single nucleotide polymorphism located in the 3-prime untranslated region (3-UTR) of the CLOCK gene. It is widely studied for its potential associations with individual sleep timing, evening chronotype, and various metabolic or psychiatric traits.
What each genotype means
Evening chronotype predisposition
Carrying two copies of the C allele has been linked in candidate gene studies to an evening diurnal preference ('night owl' tendencies), delayed sleep onset, and altered daily appetite timing. However, modern large-scale genome-wide association studies (GWAS) show mixed or modest effects, indicating that this variant alone does not dictate your circadian schedule. Individual sleep patterns remain heavily shaped by light exposure, lifestyle, and other genetic factors.
Found in approximately 4% to 10% of individuals across global populations, being slightly more common in populations of European and Hispanic descent than in East Asian ancestries.
Intermediate to evening preference
Carrying one copy of the C allele is associated in circadian candidate gene research with a slight shift toward evening preferences and somewhat later preferred bedtime. Evidence across broader population studies remains modest and inconsistent, meaning this genotype confers only a slight statistical tendency rather than an inevitable delay in your sleep-wake rhythm. Environmental cues such as daytime light exposure and consistent schedules play a dominant role in regulating sleep timing.
Carried by approximately 35% to 45% of people in European, American, and South Asian populations, and slightly less frequently in East Asian cohorts.
Typical morning-evening balance
You carry two copies of the common ancestral T allele, which represents the standard baseline rhythm without the C-allele delay in circadian timing. Studies commonly associate this genotype with standard morningness-eveningness scores and typical baseline circadian rhythms. Your overall sleep quality and chronotype continue to be governed by a complex mix of sleep hygiene, daily routines, and many other genetic loci.
Represents the most common genotype globally, found in approximately 45% to 60% of individuals in most ancestral populations.
Understanding the rs1801269 Variant
The rs1801269 variant, often referred to in literature as the 3111T/C polymorphism, is a specific change in the DNA sequence of the CLOCK gene. This gene encodes a protein that acts as a core component of the molecular circadian clock, the internal system that regulates daily biological rhythms in humans. The variant is located in the 3-prime untranslated region (3-UTR) of the gene, a segment of DNA that does not code for protein but plays a critical role in regulating how much protein is produced from the gene. Because this region helps control the stability and expression of the CLOCK mRNA, researchers have hypothesized that variations here could alter the precision or robustness of the body's internal clock, potentially leading to differences in how individuals experience sleep-wake cycles and other time-dependent biological processes.
The Role of the CLOCK Gene
The CLOCK gene (Circadian Locomotor Output Cycles Kaput) is a fundamental part of the machinery that keeps our bodies synchronized with the 24-hour day-night cycle. The CLOCK protein works in tandem with other proteins to form a feedback loop that drives the expression of genes involved in metabolism, hormone release, and sleep regulation. By influencing the timing of these processes, the CLOCK gene helps determine whether an individual is naturally inclined to be a 'morning person' or an 'evening person,' a trait known as chronotype. Because this gene is expressed in tissues throughout the body, including the brain and the digestive system, its influence extends beyond just sleep. It is also involved in regulating energy balance, appetite-related hormones like ghrelin, and the body's response to dietary intake, making it a subject of interest in studies regarding weight management and metabolic health.
Research Associations and Evidence Strength
Research into rs1801269 has produced mixed and sometimes conflicting results, leading to a classification of limited evidence strength. Many studies have explored its link to 'eveningness'—a preference for staying up late and waking up late—and delayed sleep timing. Some research has suggested that carriers of the C allele may experience shorter sleep duration or higher levels of daytime sleepiness compared to those with the TT genotype. Additionally, some investigations have looked at potential associations with psychiatric conditions, such as insomnia in patients with mood disorders, or metabolic outcomes like weight loss resistance. However, it is important to note that these findings are not universal. Other studies have failed to replicate these associations, and the effects observed are often small. Because human behavior and sleep are influenced by a complex interplay of many genes and environmental factors, the impact of this single SNP remains a subject of ongoing scientific debate rather than a settled clinical fact.
Population Frequency
The rs1801269 variant is considered a common polymorphism. Across global populations, the minor allele frequency typically ranges between 0.20 and 0.35, meaning that a significant portion of the population carries at least one copy of the C allele.
Interpreting Your Genetic Information
It is essential to understand that genetic variants like rs1801269 do not determine your health or behavior in isolation. While scientific studies look for statistical trends across large groups of people, these findings cannot predict an individual's specific sleep patterns or health outcomes. Factors such as lifestyle, work schedules, light exposure, and the influence of hundreds of other genetic variants play a much larger role in your daily life than any single SNP. You should never use information about this variant to diagnose yourself with a sleep disorder or to make medical decisions. If you are concerned about your sleep quality, weight, or mental health, the most effective approach is to consult with a qualified healthcare professional. They can provide personalized guidance based on your clinical history and current symptoms, rather than relying on isolated genetic data that may not be applicable to your specific situation.
How common is this variant?
The rs1801269 variant is common, with a minor allele frequency typically reported between 0.20 and 0.35 in global populations.
Frequently asked questions
Does the CLOCK rs1801269 variant mean I have a sleep disorder?
No. This variant is a common genetic marker associated with statistical trends in sleep timing and preference, not a diagnostic test for sleep disorders. Sleep disorders are complex conditions that require evaluation by a medical professional.
Can I change my chronotype if I have the C allele?
Chronotype is influenced by both genetics and environment. While you cannot change your DNA, lifestyle factors such as consistent sleep schedules and light exposure management can significantly influence your daily rhythm regardless of your genotype.
Is this variant linked to obesity?
Some research has explored associations between this variant and weight loss outcomes or metabolic markers. However, the evidence is mixed, and weight management is primarily driven by diet, physical activity, and overall health status.
Should I take supplements based on my CLOCK genotype?
There is no scientific evidence supporting the use of specific supplements based on the rs1801269 variant. Always consult with a doctor or pharmacist before starting any new supplement regimen.
Sources & further reading
Educational information only, last refreshed 10/17/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant in the CLOCK gene is associated with variations in circadian rhythm, chrononutrition, and metabolic parameters in adolescents.
Polymorphism in the CLOCK gene linked to sleep disturbances and metabolic health markers in adolescent populations.
Carriers of the T allele are associated with significantly shorter sleep duration.
A 3-UTR single nucleotide polymorphism in the core CLOCK gene associated with evening chronotype.
3' UTR polymorphism in the core circadian regulator gene associated with evening chronotype ('night owl' tendency) and delayed sleep phase.
CLOCK 3111T/C variant influences circadian timing; associated with eveningness and sleep-schedule preference.