CRY1 rs397514719: Understanding the Night Owl Variant
The rs397514719 variant in the CRY1 gene is a rare genetic mutation associated with familial delayed sleep phase disorder (DSPD). This variant alters the function of the CRY1 protein, which plays a critical role in regulating the body's internal circadian clock.
What each genotype means
Typical circadian timing
You carry two copies of the common G allele at this CRY1 splice site position. This genotype is not associated with the exon-skipping alteration that causes lengthened circadian periods or familial delayed sleep phase disorder. You have typical baseline genetic risk for this specific circadian trait.
Found in more than 99% of people across most global populations, including over 99.4% of individuals of European ancestry.
Delayed sleep phase tendency
You carry one copy of the rare A allele (c.1657+1G>A / CRY1Δ11), which alters a splice donor site and produces an overactive circadian repressor. In clinical studies, this dominant variant is associated with prolonged endogenous circadian periods, late-shifted sleep onset, and familial delayed sleep phase syndrome. However, penetrance can vary, and some carriers adapt without persistent daytime impairment depending on schedule and environmental cues.
Carried in a heterozygous state by roughly 0.4% to 0.6% of people of European descent and is very rare or absent in East Asian and African populations.
Marked delayed sleep phase tendency
You carry two copies of the rare splice-altering A allele in CRY1. Because the variant acts dominantly to prolong the molecular circadian clock cycle, having two copies similarly predisposes to delayed sleep onset and late-shifted physiological rhythms. Observed homozygous carriers in published family studies have exhibited delayed sleep-wake patterns consistent with delayed sleep phase disorder.
Extremely rare globally, estimated at less than 1 in 100,000 individuals, but observed in small numbers within founder cohorts and consanguineous families.
What is the rs397514719 Variant?
The variant rs397514719, often referred to in scientific literature as the c.1657+3A>C mutation, is a specific change located within the CRY1 gene. This gene provides instructions for creating a protein that acts as a core component of the human circadian clock. The mutation is a splice donor variant, meaning it interferes with the normal process of splicing, where the cell removes non-coding segments of genetic material. Specifically, this mutation causes the skipping of exon 11 during the production of the CRY1 protein. This results in a truncated version of the protein, known as CRY1Δ11, which retains its ability to bind to other clock proteins but functions differently than the standard version. Because this variant is located in a critical regulatory region, it significantly impacts how the body maintains its 24-hour rhythm.
The Role of CRY1 in Circadian Rhythms
The CRY1 protein is essential for the molecular machinery that keeps our internal clocks synchronized with the environment. Under normal conditions, CRY1 works in a complex with other proteins, such as PER, to inhibit the activity of the CLOCK/BMAL1 complex. This inhibition is a vital part of the feedback loop that dictates our sleep-wake cycles. When the CRY1Δ11 protein is produced due to the rs397514719 variant, it exhibits an enhanced ability to repress the CLOCK/BMAL1 complex. By keeping these clock genes switched off for a longer duration, the mutation effectively lengthens the internal circadian period. This shift makes it difficult for individuals to fall asleep at conventional times, leading to the characteristic 'night owl' behavior associated with delayed sleep phase disorder, where sleep onset is pushed significantly later into the night.
Research and Evidence
Research into rs397514719 has established a strong link between this variant and familial delayed sleep phase disorder. Studies, including those published in journals like Cell, have demonstrated that the mutation acts in a dominant manner, meaning that inheriting a single copy of the variant is sufficient to influence sleep patterns. Researchers have observed that individuals carrying this variant often report a history of persistent sleep-onset problems that are misaligned with societal norms. While the evidence for its role in DSPD is strong, it is important to note that sleep behavior is complex and influenced by many genetic and environmental factors. Not every person with this variant will experience the same severity of symptoms, and the scientific community continues to study how other genetic modifiers might interact with this specific CRY1 mutation to influence individual sleep phenotypes.
Population Frequency
The rs397514719 variant is considered rare in the general population. However, data suggests it is present in approximately 0.6% of individuals of non-Finnish European descent. Because it is a rare variant, it is not typically found in the majority of the population. Its prevalence can vary significantly across different ancestral groups, and current research efforts are focused on better understanding its distribution globally. While 0.6% may seem like a small percentage, it represents a significant number of people who may be predisposed to altered sleep patterns due to this specific genetic factor.
What This Information Means for You
Understanding your genetic profile regarding the CRY1 gene can provide insight into why you might have a natural preference for later sleep times. However, it is crucial to remember that this information is for educational purposes and does not constitute a medical diagnosis. If you are experiencing persistent sleep difficulties that impact your daily life, health, or well-being, you should consult with a healthcare professional or a sleep specialist. They can provide a clinical evaluation and discuss appropriate management strategies, which may include behavioral changes, light therapy, or other evidence-based interventions. Never use genetic information to self-diagnose or alter medical treatments without professional guidance. Genetic variants are only one piece of the puzzle in understanding human health, and a comprehensive approach to sleep hygiene and medical care is always recommended.
How common is this variant?
The rs397514719 variant is rare, with an estimated frequency of up to 0.6% in individuals of non-Finnish European descent.
Frequently asked questions
Can a genetic test diagnose delayed sleep phase disorder?
Genetic testing can identify the presence of variants like rs397514719, but it is not a diagnostic tool for sleep disorders. A diagnosis of delayed sleep phase disorder is typically made by a clinician based on a patient's sleep history, sleep logs, and clinical evaluation.
Is the CRY1 mutation the only cause of being a 'night owl'?
No, being a 'night owl' is a complex trait influenced by many different genes, as well as environmental and lifestyle factors. While the CRY1 variant is a known contributor, most people with delayed sleep preferences do not carry this specific mutation.
What should I do if I think I have this variant?
If you are concerned about your sleep patterns, the best course of action is to speak with a doctor or a sleep specialist. They can help you determine if your sleep issues require clinical intervention and discuss healthy sleep habits.
Does this variant affect my health in other ways?
The primary association with this variant is the regulation of the circadian clock and sleep timing. While circadian rhythms influence many aspects of health, there is no current evidence suggesting this specific variant causes other unrelated diseases.
Sources & further reading
Educational information only, last refreshed 10/7/2026. Not medical advice — these associations describe population statistics, not individual predictions.
Curious what your genotype is for rs397514719?
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 CRY1
This intronic variant in the CRY1 gene is associated with delayed sleep-wake phase disorder (DSWPD) and has been linked to variations in glycemic parameters and insulin resistance.
Variant in the CRY1 gene, which encodes a core component of the circadian clock, associated with sleep timing and delayed sleep phase.
Dominant splice-site mutation (c.1657+3A>C) in CRY1, resulting in skipping of exon 11 and associated with delayed sleep-wake phase disorder (DSWPD).
Variant in the CRY1 locus associated with sleep timing and circadian rhythm traits; distinct from rare high-penetrance mutations.
Cryptochrome 1 variant linked to sleep-wake timing variations and subjective poor sleep phenotypes.
This SNP is located in the CRY1 gene, which encodes a core circadian clock protein involved in regulating sleep-wake cycles.