Circadian Propensity
Classic morning lark, night owl, or somewhere in between—your chronotype is mostly genetic. Scheduling life around it instead of against it is the easiest health upgrade you'll ever make. Fighting it is the most exhausting.
What this measures
How your DNA shapes circadian propensity.
CLOCK, PER3, and BMAL1 are the core "clock genes" — the molecular oscillators that run a roughly 24-hour rhythm in nearly every cell. CRY1 controls how that internal day aligns with external light. ASMT contributes through melatonin synthesis. The collective network sets whether your biology naturally runs early, late, or in between.
Carriers of CLOCK morning-type variants are associated with earlier natural wake and earlier sleep; carriers of PER3 night-type variants are associated with later natural rhythms. Most clients carry combinations that produce an intermediate but distinct chronotype. CRY1 long-variant carriers are associated with delayed sleep phase — the genuinely-can’t-sleep-before-1am pattern that isn’t lifestyle and isn’t fixable through "better discipline."
Morning bright light shifts the clock earlier; evening blue light shifts it later. Consistent wake time anchors the rhythm more reliably than consistent bedtime. Meal timing influences peripheral clocks in liver and gut. Caffeine timing matters — caffeine at 2pm still affects sleep onset 10 hours later in carriers of slow-CYP1A2 variants.
Fighting your chronotype produces "social jet lag" — chronic mismatch between biology and schedule. Which combination of clock variants you carry decides whether the standard 7am–11pm cadence is biologically congruent or whether structuring your day around an actual chronotype is the missing piece.
Circadian Propensity is one specific finding in this system. Your Genomic Lifestyle Optimization Report shows where your variants place you on the sleep optimization and circadian health spectrum — and what you can do about it.
In your report
Where Circadian Propensity lives inside your Genomic Lifestyle Optimization Report.
Circadian Propensity renders as a dark-background card with a color marker calibrated to your specific variants. The card opens with the gene mechanism, shows your result at a glance via that marker, and closes with a practical, mechanism-led recommendation — what to eat, what to time, what cofactors to support.
Want to see what a real Mosaic dark card looks like? Walk through a sample report →
Questions people ask
About Circadian Propensity.
- How does my DNA influence circadian propensity?
- Your sleep architecture is set by genes that control chronotype (PER3, CLOCK, BMAL1), melatonin synthesis and clearance (AANAT, ASMT), light sensitivity (OPN4), and sleep pressure (DEC2). Forcing a 6am routine when your variants encode a late chronotype is biological friction, not a discipline problem.
- What kind of test do I need to see my Circadian Propensity result?
- Whole-genome sequencing at 30× clinical depth. Consumer SNP-chip tests like 23andMe or AncestryDNA only read ~0.02% of your DNA and miss most of the variants this analysis needs. Mosaic reads all 3 billion base pairs and produces the full 108-insight report.
- How is Circadian Propensity different from clinical lab testing?
- Clinical labs measure downstream biomarkers — blood levels, hormone values, metabolic byproducts — at a single point in time. Genomic insights like Circadian Propensity reveal the underlying variant that shapes the biology, which is constant for life. The two are complementary: labs show the current snapshot; genomics shows the long-term tendency and where lifestyle leverage is highest.
More from Sleep Optimization and Circadian Health
sleep optimization and circadian health
Ideal Sleep Duration
Restorative needs range from ~6.5 to ~9 hours between different people. Consistently short-changing your personal number—even by 30 minutes—is often the silent cause of "I sleep 8 hours, but I'm still tired." Maybe you need 8.5. Maybe you only need 7.
Read insight →sleep optimization and circadian health
Melatonin Metabolism
How quickly your body clears melatonin determines whether you wake up groggy from a 1 mg supplement, or can take 5 mg and feel nothing the next morning. Slow metabolizers need lower doses and earlier timing. Fast metabolizers can afford more flexibility.
Read insight →sleep optimization and circadian health
Melatonin Production
Natural evening melatonin rise varies up to 10-fold between people. Low producers struggle with sleep onset, no matter how good their sleep hygiene is. High producers naturally fall asleep early—sometimes inconveniently so. Light exposure and supplement timing finally make sense once you know your baseline.
Read insight →sleep optimization and circadian health
Melatonin Supplement Response
Receptor sensitivity predicts whether melatonin helps you fall asleep faster—or just gives you weird dreams and a morning hangover. If supplements have never worked for you, this might explain why. If they work too well, same answer.
Read insight →sleep optimization and circadian health
Propensity for Daytime Drowsiness
Arousal regulation differs between people. Some stay sharp and alert on 6 hours of sleep; others feel drowsy even after 9. Knowing yours separates "I'm sleeping poorly" from "my daytime alertness drive is genetically lower"—two different problems with different solutions.
Read insight →sleep optimization and circadian health
Risk of Sleep Disruption
Sensitivity to noise, light, and temperature during sleep varies genetically. High-vulnerability individuals need blackout curtains, white-noise machines, and temperature control; low-vulnerability people sleep through fireworks and wonder what all the fuss is about.
Read insight →
One test. 108 personalized findings. All yours.
Order your Mosaic kit. Receive your raw genomic data and the full Genomic Lifestyle Optimization Report in 15–20 days.