Your body runs on rhythm, not routine.
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Dear woman who has ever felt broken by her own inconsistency,
Your body runs on rhythm,
not routine.
New research on circadian biology and the menstrual cycle is rewriting what we know about women’s health — and it starts with understanding that your body was never designed to be the same every day.
Geeta Sethi, Founder — Kiyoerah
The discovery that changes everything
In April 2024, reproductive researchers published findings in Science Advances that reframed how we understand the female body. Analysing over 31,000 menstrual cycles from more than 3,000 women, they found strong evidence that the menstrual cycle is governed by an internal biological clock — a circamonthly timing system, analogous to the circadian clock that regulates our 24-hour rhythms.
“The rhythmic characteristics of the menstrual cycle are more likely explained by an endogenous clock-like timer — not by external or lunar cycles.” — Ecochard et al., Science Advances, 2024
Your body is not simply responding to external cues each month. It is operating from a deeply embedded internal timekeeper — one that, when respected, produces regularity, resilience, and wellbeing. When disrupted, it produces the opposite.
Two clocks, constantly in conversation
Your body runs on two overlapping rhythms: the 24-hour circadian clock and the monthly ovarian cycle. Research published in Sleep and Biological Rhythms (2024) confirmed that estrogen and progesterone actively alter circadian behaviour. How you sleep, when you feel most alert, and how your temperature fluctuates across a 24-hour period all shift depending on which phase of your cycle you're in.
In the luteal phase, core body temperature rises by approximately 0.3°C due to progesterone. It affects sleep quality, hunger signals, and energy availability. It is not dysfunction. It is your body doing exactly what it is designed to do.
What rhythmic living actually means
Rhythmic living means structuring how you eat, move, rest, create, and make decisions in alignment with the internal timing systems your body is already running on — rather than overriding them with a fixed external schedule. Your follicular phase favours high-output work and new beginnings. Your luteal phase favours completion, depth, and rest. This is not prescription. It is permission.
The role of scent in anchoring rhythm
The olfactory system has the most direct neurological pathway to the limbic system of any sense. A consciously chosen scent, applied at a particular phase of your cycle as part of a deliberate ritual, can function as a biological anchor — signalling to the nervous system which season it is in.
Your cycle is not an inconvenience to be managed. It is a timing system of remarkable precision — and it deserves to be treated as such.
With science and care,
Geeta
FOUNDER, KIYOERAH
