Use Case: Peak Hours
Find when your brain performs best
The Problem
You schedule important work whenever it fits your calendar, not when your brain is sharpest. The 2pm meeting might be hitting your cognitive trough, reducing your performance in key moments.
The Solution
Thalen maps your personal circadian cognitive rhythm. Your data might show: 'Morning peak = 1680, afternoon trough = 1450.' Schedule demanding work for your 1680 hours, not your 1450s.
How It Works
How to map your circadian rhythm
Build a personal cognitive profile across different times of day.
Test at different times over 2 weeks
Vary your testing time across the day. Some days test at 8am, others at noon, 4pm, or 8pm. Aim for at least 3 data points per time slot.
Keep other variables constant
Sleep, caffeine, meals: try to keep these consistent. You want to isolate the effect of time-of-day on your cognitive performance.
Let Thalen build your circadian profile
After 2 weeks of varied testing times, Thalen maps your performance across the day using cosinor regression to find your personal circadian rhythm.
Schedule work around your peaks
Use your data to schedule demanding cognitive work during peak hours. Save routine tasks for your troughs.
Surprising Results
Discovering a 10am peak: 1680 vs 1510 at 8am
A user assumed they were a 'morning person' and scheduled deep work for 8am. After 3 weeks of testing at varied times, their data revealed a different story: their actual cognitive peak was 10am-noon, with an unexpected secondary peak in the evening.
| Metric | Before | After | Change |
|---|---|---|---|
| 8-9am (Morning) | Expected peak | 1510 | Below average |
| 10am-12pm (Late Morning) | Expected average | 1680 | Actual peak (+170) |
| 2-4pm (Afternoon) | Expected trough | 1450 | Confirmed trough |
| 7-9pm (Evening) | Expected low | 1590 | Secondary peak |
Key Insight
The 170-point difference between 8am (1510) and 10am-noon (1680) is substantial. It's the difference between mid-Potent and approaching Coherent. According to Schmidt et al. (2007), individual circadian differences of 4-6 hours are common. This user restructured their calendar: deep work 10am-12pm, meetings in the afternoon trough.
This is a hypothetical example for illustration. Individual results vary based on baseline, consistency, and intervention.
The Science
Circadian rhythms and cognition
Your cognitive performance follows a circadian rhythm, a roughly 24-hour cycle driven by your internal clock that affects measurable cognitive performance.
According to Valdez (2019), cognitive functions including attention, working memory, and executive function all show circadian variation. The difference can be significant: performance gaps between peak and trough can exceed the effect of mild sleep deprivation.
"Circadian variation in cognitive performance can be as large as 10-20%, comparable to the effects of moderate alcohol intoxication or 24 hours of sleep deprivation."
The problem: generic advice like "mornings are best for deep work" ignores individual variation. Your chronotype (morning lark vs. night owl) dramatically shifts when your cognitive peak occurs.
Apply Your Data
Schedule around your rhythm
Peak Hours
Schedule: Complex problem-solving, strategic thinking, creative work, important decisions, learning new material.
Protect these hours aggressively
Trough Hours
Schedule: Email, administrative tasks, routine meetings, tasks you could do "on autopilot."
Don't waste peaks on these
Meetings
If you control the timing, schedule high-stakes meetings during your peaks. Routine syncs can go in troughs.
Your data gives you negotiating power
Secondary Peaks
Many people have a smaller evening peak. Use it for side projects or catching up on demanding work.
Often overlooked but valuable
Get early access.
Thalen is coming to iOS first. Join the TestFlight beta and start building your cognitive baseline.
Free. Your data stays on your device. No account required.