The luteal phase is where so many women notice changes: in mood, energy, sleep, and cravings, yet it remains one of the least understood parts of the menstrual cycle. In The Period Brain, Dr. Sarah E. Hill sets out to have the luteal phase explained in a way that finally matches women’s experiences.
In this conversation, she shares why this stage has been historically understudied, what drives common luteal phase mood swings and symptoms, and how everyday habits can either make them worse or help ease the load.
From calorie needs that rise by up to 11% in the luteal phase, to the surprising ways progesterone reshapes brain circuits, Dr. Hill connects the science with practical tools, from nutrition and training to stress buffers and sleep strategies.
This conversation offers a preview of the insights readers will find in her new book and a reminder that biology isn’t a problem to push through, but a rhythm we can work with.
1. What inspired you to write The Period Brain at this moment in time, and how did your research lead you to focus on the luteal phase as historically understudied?
For years I’ve obsessed over the fact that it’s so biologically weird that almost all women have the experience of feeling terrible in the week or so leading up to their periods. When I looked for answers, my research kept pointing to a gaping blind spot: we’ve built health science around the “male-as-default” model and treated women’s hormones as noise to be minimized.
The luteal phase, when progesterone leads, has been especially neglected, even though that’s when many women feel it most in mood, energy, sleep, cravings, and stress reactivity. The Period Brain shines a light there so women get tools that match their biology, not fight it.
2. You argue that many health, diet, and fitness rules are designed for the first half of the cycle. Could you share one or two examples where that mismatch causes real problems?
Two big ones are:
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Aggressive fasting + 5 a.m. HIIT
That combo may feel great in late follicular (higher estrogen, more stress resilience). In late luteal, it can backfire: sleep tanks, cravings spike, cortisol climbs, and you white-knuckle your way to “falling off the plan.”
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Permanent calorie deficit + endless cardio
Works (kind of) in follicular; in luteal it often means under-fueling a higher metabolic demand, worsening mood, sleep, and adherence. The “willpower problem” is usually a biology mismatch problem.
3. In The Period Brain, you note that during the luteal phase, some women burn up to 11% more calories. How should this shape nutrition and meal planning?
Treat it like a planned re-feed, not a failure. For many, that’s ~100–300 extra kcal/day. Front-load protein, add complex carbs (especially with dinner for sleep), keep healthy fats, and don’t fear a little extra salt and magnesium-rich foods for bloating/cramps. Pre-stock luteal-friendly meals so you’re not negotiating with your future self at 10 p.m.
4. What’s one finding that surprised you most while writing this book?
How much progesterone and its neuroactive metabolites (like allopregnanolone) reshape brain function, calming threat circuits for many women, and how modern stress, sleep loss, under-fueling, and inflammation can blunt those benefits. The same hormone that should help can feel awful in the wrong environment.
5. You write that progesterone has “addiction-busting” properties. Could you explain what this means and how strong the evidence is?
Progesterone’s metabolites enhance GABA-A signalling, which generally dampens stress and cue-reactivity. Across studies, higher progesterone (or short-term progesterone administration) is associated with lower craving and use for substances like nicotine and alcohol. It’s not a magic bullet, but it’s a biologically plausible, reproducible effect; we need more large RCTs to define who benefits, when, and how much.
6. How might hormonal contraceptives affect what you call the Period Brain? Does your advice apply differently depending on whether someone is on or off birth control?
Most hormonal contraceptives flatten ovarian hormone rhythms and replace them with synthetic progestins (which aren’t the same as progesterone). Some women feel wonderfully steady; others notice mood, desire, or stress changes. The core advice still helps: sleep, anti-inflammatory nutrition, resistance training, sunlight, stress tools, but I ask readers to track their own pattern (pill days vs. placebo days; IUD placement timeline) and tune levers accordingly.
7. For readers with PMDD, which tools in your book are especially helpful beyond what works for PMS?
Start with the PMDD Buffer Week in the book:
- A pre-planned 7–10 day protocol: sleep protection, extra calories from whole foods, lower-intensity training, caffeine trim, magnesium + omega-3 focus.
- Threat-downshifting: morning light, breath work, shorter to-do lists, and scripted boundaries.
8. You recommend “anti-inflammatory foods and habits” for easing PMS. Could you highlight a few approachable examples?
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Habits: 8 hours in bed, morning light, and daily activity. I for one am a huge fan of the morning walk. It gives me movement, morning light, and acts as a moving meditation. Also, spend time with those you love. This is another way to lower inflammation and support hormones.
- Swap outs: fewer ultra-processed foods, less alcohol (especially late luteal), and move your morning coffee routine outside. Getting morning sunlight into your eyes helps set your circadian rhythms and will give you better sleep.
9. For readers designing their lives around their cycles, at work, in wellness, or relationships, what “cycle-aware” habits do you see as the highest leverage?
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Plan your month, not just your day.
Front-load big pitches, heavy lifts, and social sprints in mid/late follicular; build buffers in late luteal (sleep, white space, batch admin, fewer evening commitments).
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Fuel to phase.
Slight calorie uptick + protein/complex carbs in luteal; creatine + lifting focus in follicular.
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Mood-safe systems.
Pre-written “not now, next week” scripts, pre-shopped meals, and hard bedtime alarms.
10. Why has mainstream science been so slow to take the menstrual cycle seriously as a brain-health issue?
We built biomedicine on a male baseline, then “controlled” women’s variability away, often studied them only in early follicular or not at all.
Add pregnancy concerns, cost/logistics, and the myth that women are “too variable,” and you get decades of missing data. We’re finally correcting course.
11. If a reader takes away just one practical tool from your book, what would you hope it is?
The Luteal Buffer Plan: a short, repeatable protocol that protects sleep, increases calories from whole foods, trims stimulants, shifts training, and pre-plans boundaries. It’s simple, compassionate, and it works.
12. What cultural narratives about women’s cycles frustrate you most, and how do you hope The Period Brain rewrites them?
The lazy tropes: “women are irrational,” “PMS is an excuse,” “just push through”, erase biology.
The rewrite: cyclical intelligence. When women align behavior with physiology, they perform better, feel better, and stop blaming themselves for problems that were design flaws in the plan.
13. What would a cycle-conscious workplace, classroom, or society look like?
Flexible when work gets done, not just where. Monthly project cadences with built-in buffer weeks, access to daylight and real food, and a culture where saying “this is a low-bandwidth week for me; here’s how I’ll deliver” is normal, not stigmatized.
14. Where can readers find your book and follow your work?
The Period Brain is available wherever books are sold. On sale from September 30, 2025. Pre-orders are open now.
You can find my work at sarahehill.com and on Instagram @sarahehillphd. If you want deeper dives, my newsletter will be linked there as well.
While this blog discusses health topics, it is not a substitute for professional medical advice. Always consult your doctor or other qualified healthcare provider regarding any question you might have regarding your health.
In Conversation With
Dr. Sarah E. Hill is a speaker, consultant, award-winning researcher, professor, and media expert. She is the author of This Is Your Brain on Birth Control and the forthcoming The Period Brain (September 2025). With 100+ scientific publications, her work has been featured in The New York Times, The Washington Post, Scientific American, The Economist, and on shows like Good Morning America and Today.