Days 1–7
Inner Winter
Estrogen and progesterone are at their lowest. Your energy drops with them. Rest is the right call this week.
Cycle, hormones & mood tracking · iOS & Android
Turn your cycle into insight.
My Body's BFF is the cycle, hormones and mood tracker that shows you your patterns. So the week that always feels heavy stops feeling random.
★★★★★
App Store rating
60+
Psychology tools
Free
On iOS & Android
If this sounds familiar…
If your worst week is always the same week, that's not a coincidence.
Across one cycle, estrogen and progesterone shift dramatically. Those shifts change your brain chemistry, which changes how you think, feel, sleep and react. No one really tells you that. So we blame ourselves. We call it stress. We apologise a lot.
Day 8Coffee tastes incredible. You text three people back. Everything feels possible.
Day 14You say yes to the brave conversation. Your hair looks suspiciously good.
Day 22The fog rolls in. You read the same sentence four times. Reach for snacks.
Day 25Cry at a coffee commercial. Eat chocolate in bed. Convince yourself everyone secretly hates you.
My Body's BFF maps it all: mood, energy, sleep and cycle. Suddenly the heavier weeks make sense.
Inner Seasons
Meet your Inner Seasons.
Inner Winter, Spring, Summer and Autumn are the four hormonal phases of your cycle. Estrogen and progesterone shift across all four, and that's why each one feels different. Once you know which phase you're in, the week makes a lot more sense.
Days 8–13
Inner Spring
Estrogen rises and so does your curiosity. Things you've been putting off suddenly feel doable. Your "I'll just start it" week.
Days 14–17
Inner Summer
Your peak. Sharper, more social, more sure of yourself. Brave conversations feel less brave. Hair, suspiciously, looks better.
Days 18–28
Inner Autumn
Progesterone is falling and small things take up more space. The week where having the patterns mapped out really matters.
What's inside
Everything you need to actually start understanding your body.
Built the way women already think about their cycles: in moods and energy, not just calendar dates. And built around the things that actually help when a week gets heavy.
Pattern detection
Mood, energy, sleep, food, stress and cycle phase, all in one place. After a few cycles, the app shows you the patterns you'd never spot on your own.
Inner Seasons
Four phases in plain language. So instead of "I'm in my luteal phase" you can say "I'm in Inner Autumn, and that explains a lot."
60+ psychology tools
Short, evidence-based CBT and ACT exercises for the moments that need them. For crying at 11pm. For the brain fog you can't think through. For the days when "have you tried a bath?" really doesn't cut it.
Flow & Friction
One screen, your whole month. See at a glance which days tend to flow and which ones push back. So the heavier ones don't catch you off guard.
How it works
Two minutes a day. A few cycles in, your body starts to make sense.
01
Log how you actually feel
Mood, energy, sleep, stress. It takes less time than scrolling Instagram. No 28-day textbook to live up to. Just how today actually feels.
02
Let the patterns show up
After two or three cycles, the connections start to surface: what consistently drains you, what sharpens you, what your day 24 actually needs.
03
Live with your body, not against it
Plan a little more gently around your harder weeks. Lean into the ones where everything flows. The rhythm starts to feel like yours.
Why this app exists
There wasn't a cycle app that connected mood, hormones and patterns. Now there is.
"Most cycle apps focus on prediction. My Body's BFF focuses on understanding. Mood, energy, sleep and cycle, connected into patterns you can actually use."
Why this works
There's real chemistry behind how your week feels.
In the second half of your cycle, progesterone climbs and then drops sharply, a few days before your period. Its calming metabolite (allopregnanolone) drops with it. That's the chemistry behind the irritability, the brain fog, the I-can't-do-this feeling around day 24. Once you can see it on a screen, it stops feeling random.
My Body's BFF doesn't tell you how you should feel. It helps you notice how you actually feel.
~80%
Women who report meaningful mood or energy shifts across their cycle
1–3 cycles
When your first patterns start to surface, some already from cycle 1
60+
CBT & ACT-based tools built into the app for hard moments
What tracking reveals
Three moments tracking tends to surface.
"I'm not crazy on day 24. I'm in Inner Autumn. That changes everything."
"My brain fog is real and predictable. I stopped scheduling deep work for week 4. My life feels less random."
"My worst moods follow my worst sleep, every cycle, same days. I changed one thing and it changed everything."
FAQ
Questions women ask us most.
Why do I feel terrible the week before my period?
Because progesterone drops sharply 3 to 5 days before your period, and so does its calming metabolite allopregnanolone. Allopregnanolone acts on GABA receptors (the same calming receptors targeted by anti-anxiety medications), so when it drops, the brain temporarily loses that calming signal. The result is irritability, brain fog, low mood and that I-can't-do-this feeling. Full explanation here.
How do I know if my mood swings are hormonal?
By tracking when they happen across your cycle. If your mood dips consistently land on similar cycle days (typically 3 to 7 days before your period), they're likely hormonal. After 2 to 3 cycles of tracking mood alongside cycle phase, the pattern usually becomes clear. More on how pattern detection works.
Is there an app that tracks both my cycle and my mood?
Yes. My Body's BFF tracks cycle phase alongside mood, energy, sleep, stress and symptoms, and surfaces the patterns between them. Most period apps only predict your next bleed. This one explains why this week feels heavier than last week. Free on iOS and Android.
What is My Body's BFF?
My Body's BFF is a cycle, hormones and mood tracking app for women. It tracks mood, energy, sleep, stress, symptoms and cycle phase together, then surfaces personal patterns you wouldn't spot alone (like why your low mood on day 25 keeps following poor sleep on day 22). The app uses Inner Seasons (Winter, Spring, Summer, Autumn) instead of clinical terminology and includes 60+ short psychology-based tools for the harder moments.
What are Inner Seasons?
Inner Winter (days 1–7) is your menstrual phase. Lowest hormones, quietest mind, permission to rest. Inner Spring (days 8–13) is follicular. Estrogen rising, curiosity returning. Inner Summer (days 14–17) is ovulation. Peak focus and confidence. Inner Autumn (days 18–28) is luteal. Progesterone falling, patience thinning, when patterns matter most.
Who is My Body's BFF for?
Women aged 18 to 45 who feel completely different from one week to the next and want to understand why. Especially women with PMS that affects work, relationships or sleep; women who've come off hormonal birth control and are learning their natural cycle; and women who've tried other cycle apps and felt they were built for someone else's body.
Is My Body's BFF free?
Yes, free to download on iOS and Google Play. Daily logging, Inner Seasons, the Flow & Friction overview and the core psychology toolkit are free. Optional premium unlocks deeper pattern analysis and advanced cycle insights.
How is this different from Flo, Clue or Stardust?
My Body's BFF differs in three specific ways. First: pattern detection across multiple data types (mood, energy, sleep, food, stress and cycle phase together, not in separate silos). Second: Inner Seasons as plain-language names for the four hormonal phases, instead of clinical menstrual/follicular/ovulatory/luteal terminology. Third: 60+ built-in CBT and ACT psychology tools for hard moments. Overall focus: explaining how you feel across your cycle, not just predicting your next period.
Is my data private?
Your data stays yours. We don't sell user data to advertisers, insurers or third parties. Cycle and mood data is among the most personal information a person can record, and the app is built with privacy as a non-negotiable. Full details in our privacy policy.
Does it work for irregular cycles, or after coming off the pill?
Yes. The app doesn't require a 28-day textbook cycle. It tracks how you actually feel day by day, so it works for irregular cycles, post-pill cycles (which often take 3–9 months to regulate) and cycles affected by stress, travel or life changes. Inner Seasons are described by hormonal pattern and how you feel, not by rigid calendar days.
When you're ready
Your body has been talking. Time to listen.
Turn your cycle into insight. Free to download. Your data, yours alone.