Circadian Hormone Rhythm Tools
Circadian hormone rhythms show that hormone values depend strongly on time of day, sleep timing, wake timing, and schedule alignment. A value that looks high at one time may be expected near a normal peak, while the same value may be unusual near a trough. This calculator focuses on measurable rhythm phase, expected peak and trough timing, measured-versus-expected comparison, and circadian mismatch scoring.
Core idea
The calculator first converts clock time, sleep time, and wake time into minutes after midnight. A phase offset can then shift the expected rhythm to model delayed sleep, time-zone change, or night-shift work.
\[
\begin{aligned}
\Delta t_{\mathrm{phase}}
&= \mathrm{phase\ shift\ hours}\cdot 60
\end{aligned}
\]
The selected hormone determines the expected daily pattern. Cortisol usually peaks near the morning wake period, melatonin rises around sleep onset and peaks during the night, growth hormone often pulses early in sleep, TSH tends to rise during the evening or night, and insulin sensitivity is often higher during the daytime than during the biological night.
How the result is interpreted
The expected hormone value at the selected clock time is compared with the measured value. If the measured value falls within the expected range, the rhythm is considered consistent for that time. If it falls outside the expected range, the calculator estimates whether the mismatch is mild or strong.
The circadian mismatch score combines measured-value deviation, schedule displacement, and phase-shift size.
\[
\begin{aligned}
S_{\mathrm{mismatch}}
&= 42\cdot D_{\mathrm{measured}}
+ 5.2\cdot |\Delta t_{\mathrm{wake}}|
+ 2.2\cdot |\Delta t_{\mathrm{phase}}|
\end{aligned}
\]
A low score suggests an aligned rhythm, a moderate score suggests a mildly shifted rhythm, and a high score suggests a strongly shifted or disrupted rhythm. The calculator also reports the expected phase, such as morning peak, night peak, trough, rising phase, or transition phase.
Common pitfalls
The most common mistake is interpreting a hormone value without considering the measurement time. Another mistake is comparing a delayed or night-shift schedule with a normal daytime schedule. Sleep timing changes the expected peak and trough anchors, so the same hormone level may need a different interpretation.
When to use this tool
This tool is useful for learning endocrine timing, circadian physiology, hormone peak and trough patterns, shift-work effects, delayed sleep schedules, and measured-versus-expected rhythm comparison. It is an educational model and should not be used for diagnosis or treatment decisions.
