Most cycle education uses clinical terms: menstrual, follicular, ovulatory, luteal. They're accurate. They're also the kind of words that don't quite land when you're trying to figure out why this week feels so different from last week.
Inner Seasons is a way of naming the same four phases of the menstrual cycle in everyday language. Winter, Spring, Summer, Autumn. Same biology, same hormones, just words that actually feel like something.
The seasons aren't a replacement for the medical terms. They sit alongside them. The point is to make it easier to recognize what your body is doing, without needing a biology degree to do it.
Here's what each Inner Season looks like, hormonally and practically. The boundaries aren't strict (cycles vary, see our piece on the 28-day myth), but the broad pattern holds for most cycles.
Inner Winter
What's happening
Estrogen and progesterone are at their lowest point in your cycle. The lining of your uterus is shedding. This is your period.
How it tends to feel
Low energy. Quieter mind. More sensitivity. Sometimes cramps, sometimes deep tiredness. A pull toward doing less.
The science
Estrogen influences serotonin and dopamine signalling in the brain.1 When estrogen has just dropped at the end of the previous cycle and stays low at the start of this one, those mood-supporting neurotransmitters are at their lowest too. That's part of why energy, motivation and confidence often dip in the first few days.
Body temperature is at its lowest point in the cycle. Inflammation, especially in those with painful periods, can sap energy further. The pull toward rest isn't laziness. It's biological.
What this phase is actually for
Recovery and reset. Even though hormones are at a low point, FSH (follicle-stimulating hormone) is already starting to rise, beginning the build-up to the next ovulation. So Inner Winter is both an ending and a quiet beginning.
A note on cramps
Period pain is real and biological (caused by prostaglandins triggering uterine contractions), but very heavy or severely painful periods aren't something to just power through. If your period regularly stops you from working, sleeping or moving, it's worth talking to a doctor.
Inner Spring
What's happening
Estrogen is rising. FSH has prompted follicles in your ovaries to develop. One dominant follicle is preparing to release an egg around day 14.
How it tends to feel
Energy returns. Curiosity comes back. Sleep often improves. Motivation creeps in. Many women find their best ideas in this phase.
The science
Rising estrogen boosts serotonin and dopamine signalling. It also enhances BDNF (brain-derived neurotrophic factor), which supports learning and neuroplasticity.2 Verbal memory and verbal fluency tend to peak as estrogen climbs. Mood is more stable. Stress tolerance is higher.
What this phase is actually for
Starting things. Biologically the phase builds toward the potential of ovulation, but cognitively it's about engagement and growth. If you can choose when to plan a new project, take on something challenging or push through difficult learning, this is the part of the cycle that gives you the most biological support.
Inner Summer
What's happening
Estrogen peaks. Then LH (luteinizing hormone) surges, triggering ovulation. Testosterone bumps up briefly. After the egg releases, the empty follicle becomes the corpus luteum and starts producing progesterone.
How it tends to feel
Peak energy. Sharper. More confident. More social. Often more attractive-feeling. Many women notice a libido peak around this time.
The science
The estrogen peak supports cognitive performance, verbal fluency and confidence. The small testosterone increase contributes to libido and motivation.3 Stress resilience tends to be highest. Skin often looks better, partly because estrogen supports collagen production and skin hydration.
There's also a small body temperature dip just before ovulation, then a rise just after. That's the classic biphasic temperature pattern that confirms ovulation has happened.
What this phase is actually for
Connection and reach. Biologically the phase is about fertility, but cognitively and socially it's about engagement with the world. If you have a brave conversation to have, an ask to make, a difficult meeting to prepare for, this is the phase where your biology gives you the most help.
It's also short. About three to four days. If you've ever wondered why you only feel "fully yourself" for a small part of the month, this is partly why.
Inner Autumn
What's happening
Progesterone is rising, then drops sharply about three to four days before your next period. Estrogen also has a small secondary peak, then falls alongside progesterone.
How it tends to feel
Slower. More sensitive. Lower frustration tolerance. Things that didn't bother you start to. Brain fog often appears in the late luteal days. Sleep can become more fragmented. Energy drops.
The science
Progesterone gets metabolised into a compound called allopregnanolone, which acts on GABA receptors in your brain. GABA is your main calming neurotransmitter.4 When allopregnanolone is high (mid-luteal), it can feel calming. When it drops sharply (late luteal), the brain loses that calming signal. The result is anxiety, irritability, low frustration tolerance and that I-can't-do-this feeling around day 22 to 25.
Estrogen dropping affects serotonin and dopamine in the same direction. That's part of why low mood often shows up in the late luteal.
For some women, this drop hits very hard. PMS affects most women to some degree. About 3 to 8% have PMDD (premenstrual dysphoric disorder), a more severe form.5 If your luteal phase regularly involves real interference with your work, relationships or mental health, it's worth a medical conversation.
What this phase is actually for
Reflection. Editing. Noticing. Finishing. The slower, more sensitive state lets you see what isn't working that might have been invisible during Inner Summer's confidence.
This is also the phase that benefits most from tracking. Inner Autumn is when your patterns become loudest. Your body broadcasts what's been building up for the past three weeks.
Why this framework helps
When you can name where you are in your cycle, two things change.
First, you can stop guessing why you feel the way you feel. The mood swings, the brain fog, the inexplicable tears, the week where everything feels possible. They aren't random. They line up with your hormonal state.
Second, you can plan around it. Schedule deep thinking work for Inner Spring or Summer. Block out lighter weeks for Inner Autumn. Move social plans toward your sharper days. Give yourself permission to do less in Inner Winter.
This isn't about hyperoptimizing or living by your cycle like a strict calendar. It's about working with your body's rhythm instead of fighting it.
Track your Inner Seasons.
My Body's BFF tracks mood, energy, sleep and cycle, and shows you the patterns underneath. Free on iOS and Android.
Download the appA note on irregular cycles, hormonal birth control, and other realities
The descriptions above are based on a typical ovulatory cycle. A few common variations:
- Irregular cycles: the phases still happen, but the timing varies. Inner Autumn might be longer some months than others.
- Hormonal birth control: most forms suppress ovulation, so there's no natural Inner Summer. The pill, ring, patch or hormonal IUD replace your natural fluctuations with a steadier hormonal level. Some women still feel patterns, others don't.
- Perimenopause: cycles become more variable as progesterone production declines. Inner Autumn often intensifies or shifts.
- Post-pill: cycles can be irregular for 3 to 9 months while the hypothalamic-pituitary-ovarian axis recalibrates.
The shorthand of "days 1 to 7" works for an average cycle but isn't a rule. The point of Inner Seasons isn't to fit you into a textbook. It's to give you language for what your body is already doing.