The science behind your cycle.
Guides on menstrual health, biometrics, and how your body works across every phase.
Why Do I Feel So Tired Before My Period?
Pre-period fatigue is one of the most common cycle symptoms. Learn why progesterone, iron loss, and disrupted sleep make the late luteal phase so draining — and what you can do about it.
How Your Menstrual Cycle Affects Sleep
Sleep quality shifts across your cycle — from lighter sleep in the luteal phase to better recovery after your period. Here's what the research says and how to track it.
What Is the Luteal Phase and Why Does It Matter?
The luteal phase is the second half of your menstrual cycle — and it's where most PMS symptoms, energy dips, and mood changes originate. Here's a clear, research-backed explanation.
HRV and Your Menstrual Cycle: What Heart Rate Variability Reveals
Heart rate variability changes predictably across your menstrual cycle. Learn what HRV patterns mean for each phase, and how to use this data to understand your body better.
Basal Body Temperature and Ovulation: A Complete Guide
Basal body temperature (BBT) rises after ovulation due to progesterone. Learn how the thermal shift works, how wrist temperature tracking compares, and what the data really tells you.
PMS vs. PMDD: Understanding the Difference
PMS and PMDD share similar symptoms but differ dramatically in severity. Learn how to tell them apart, what the diagnostic criteria are, and when to seek help.
How to Track Your Cycle Without an Account or Cloud Storage
Most period tracking apps require accounts and store your data on remote servers. Here's why that's a problem and how to track your cycle with full privacy.
What Your Apple Watch Can Tell You About Your Cycle
Your Apple Watch collects wrist temperature, HRV, heart rate, and sleep data every night. Here's how each metric connects to your menstrual cycle phases.
Why Your Energy Levels Change Throughout Your Cycle
Energy highs and lows across the month aren't random — they're driven by hormonal shifts in each cycle phase. Here's the science behind the pattern and how to work with it.
Understanding Ovulation Symptoms and Signs
Ovulation produces subtle but detectable symptoms — from cervical mucus changes to mittelschmerz pain. Learn the evidence-based signs and how to confirm ovulation with data.
Exercise and Your Menstrual Cycle: When to Push and When to Rest
Your body's capacity for exercise changes across your menstrual cycle. Learn which phases support peak performance and when recovery should take priority.
What Causes Irregular Periods? Common Reasons and When to See a Doctor
Irregular periods can result from stress, PCOS, thyroid issues, or lifestyle factors. Learn the most common causes, what's considered 'normal' variation, and when medical evaluation is warranted.
Track your cycle with real body data.
Ovuly uses your Apple Watch signals — HRV, wrist temperature, sleep — to help you understand your cycle beyond calendar predictions.