Cycle IntelligenceComing Soon

Your cycle is a signal. We're the first to read it properly.

Cycle Intelligence adjusts your HRV scores, sleep insights, and recovery guidance for every phase. We're building it now — be first in when it's ready.

Your cycle, understood

Four phases. Four different bodies. One platform that knows the difference.

Tap a segment to explore each phase.

Follicular
Days 1–13
FollicularDays 1–13

Peak readiness.

Hormones at their most favourable. HRV is highest, sleep is best, stress resilience peaks. The body is primed — Fueld knows it.

OvulationDays 13–15
Early LutealDays 15–21
Late LutealDays 22–28

Smarter scores

Your HRV score, finally telling the truth.

Most platforms give you a red alert when your late-luteal HRV dips. Fueld shows you the cycle-adjusted score alongside the raw score — because there's a difference between biology and a warning sign.

Raw HRV
Cycle-adjusted HRV
Day 1 (period)FollicularOvulationLutealDay 28
3–9%
lower HRV in the luteal phase
Peer-reviewed: progesterone shifts autonomic balance toward sympathetic dominance — it's physiology, not stress.
0.4°C
wrist temperature rise after ovulation
Apple Watch Series 8 and Ultra capture this nightly. Fueld uses it to detect cycle phase even before your period app does.
6%
lower sleep efficiency in late luteal
Not a sleep hygiene problem — a hormonal artefact. Fueld flags it in context so you stop blaming your wind-down routine.

In the app

Cycle intelligence woven through everything.

Cycle awareness isn't a separate tab. It lives in every score, every chart, and every AI response — so you always have the full picture.

  • Cycle context card
    Phase, day, and predicted next phase — always at the top of your Health tab when you're cycle-aware.
  • Phase-adjusted scores
    Every HRV, sleep and recovery score shows both the raw value and your cycle-adjusted reading.
  • Cycle beat in your Health Story
    Your weekly AI-generated health summary includes a Cycle beat — so context is always part of the picture.
  • AI chat that understands your phase
    Ask 'is my low HRV a problem?' and get an answer that accounts for where you are in your cycle — not a generic 'scale back' response.
Fueld AI Chat

Why do I feel like a completely different person every week?

Day 24 · Late luteal · Progesterone at peak

Because you are. Your follicular phase brings rising oestrogen — sharper focus, faster recovery, higher energy. By late luteal, progesterone dominates, your core temperature rises 0.4°C, and your body is conserving resources. What feels like a mood is a measurable physiological shift.

Secure · Privacy-stripped · AI-powered

For professionals

Your female clients are carrying a signal your tools ignore.

With client consent, the Fueld portal surfaces cycle context alongside every other health pillar. Late-luteal fatigue, disrupted sleep, and lower training readiness are flagged in context — not as unexplained anomalies.

Portal view — client health snapshot
Cycle phaseLate luteal · Day 24
HRV today48 ms (−6% vs. follicular avg)
Sleep efficiency79% (−8% vs. follicular avg)
Fueld notePhase-expected. Not indicative of stress overload.

The evidence

Grounded in peer-reviewed research.

Fueld's cycle mechanic is built on published science — not wellness content. Every insight is educational and observational; it is a prior that your daily wearable data always overrides.

Sports Medicine2025

Wearable-derived HRV across the menstrual cycle — living systematic review

HRV is 3–9% lower in the luteal phase across wearable cohorts.

Read paper
npj Digital Medicine2025

Cardiovascular amplitude and menstrual regularity

New metric correlating HRV fluctuation magnitude with progesterone.

Read paper
Biological Psychology2024

PMS, HRV, and attentional control across the cycle

Luteal HRV drop is more pronounced in high PMS-severity users.

Read paper
Sleep and Breathing2024

Sleep architecture across the menstrual cycle — EPISONO database

Mid-late follicular phase shows 89.9% sleep efficiency vs 83.7% in luteal.

Read paper

Fueld does not provide medical advice. Cycle context is educational and observational. Always consult a qualified health professional for clinical guidance.

Cycle Intelligence

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