The week before your period is the late luteal phase of your menstrual cycle. In a typical 28-day cycle, the luteal phase spans roughly day 15 through day 28, beginning after ovulation and ending when your period starts. That final week, sometimes called the late luteal phase, is when progesterone and estrogen are dropping sharply, and it’s the window most associated with PMS symptoms.
What Happens During the Luteal Phase
After ovulation, the structure left behind on your ovary (called the corpus luteum) starts pumping out progesterone. Both progesterone and estrogen climb through the middle of the luteal phase, peaking around days 19 to 22. If pregnancy doesn’t occur, those hormone levels plummet in the final week before your period. That rapid decline is what triggers your uterine lining to shed and menstruation to begin.
This hormonal arc creates two distinct halves within the luteal phase itself. The early-to-mid portion is relatively calm, with high, stable progesterone. The late portion, your last seven or so days before bleeding, is defined by falling hormones and the physical and emotional shifts that come with them.
Why You Feel Different That Week
The drop in estrogen during the late luteal phase sets off a chain reaction in your brain. Declining estrogen prompts the release of stress-related chemicals while simultaneously reducing levels of serotonin, dopamine, and other mood-regulating neurotransmitters. Progesterone also influences serotonin turnover, and research suggests it amplifies the brain’s stress response, particularly in the days just before menstruation.
This is the biological basis of PMS. Common symptoms include bloating, breast tenderness, headaches, back pain, constipation, fatigue, food cravings, irritability, anxiety, and mood swings. Symptoms often worsen progressively through the week and tend to spike about two days before your period starts, then improve quickly once bleeding begins and hormone levels bottom out.
Your Body Runs Warmer and Hungrier
Progesterone acts like a mild thermostat adjustment. During the entire luteal phase, your resting core body temperature sits 0.3°C to 0.7°C higher than it does in the first half of your cycle. This is the basis for basal body temperature tracking: a sustained temperature rise confirms ovulation has occurred. You may notice feeling slightly warmer, sleeping less comfortably, or sweating more easily during this time.
Your metabolism also speeds up. Studies that verified cycle phases with blood hormone levels found that daily energy intake increases by roughly 160 to 530 calories during the luteal phase compared to the first half of the cycle. Your body genuinely needs more fuel, partly because protein breakdown increases during this time. So those stronger-than-usual cravings aren’t just in your head. They reflect a real metabolic shift.
PMS vs. PMDD
Most people experience mild premenstrual symptoms that are annoying but manageable. About 5% to 8% of women have moderate to severe symptoms that meaningfully disrupt daily life. Of those, 3% to 8% meet criteria for premenstrual dysphoric disorder, or PMDD, the most severe form of premenstrual symptoms.
PMDD is classified as a depressive disorder. It involves at least five symptoms from a defined list, including markedly depressed mood, intense anxiety, emotional instability, persistent anger, loss of interest in usual activities, difficulty concentrating, severe fatigue, major appetite changes, sleep disruption, and feeling overwhelmed or out of control. The key distinction is severity: these symptoms are intense enough to interfere with work, relationships, or basic functioning. They also follow a strict pattern, appearing in the late luteal phase and resolving within a few days of your period starting. If your premenstrual week regularly feels debilitating rather than uncomfortable, PMDD is worth exploring with a provider.
Exercise and Energy in the Late Luteal Phase
You may have seen advice to scale back workouts during this phase, and the instinct makes sense given how fatigued many people feel. But the research on menstrual cycle phase and exercise performance is surprisingly inconclusive. Reviews of available studies have found the effects are small and highly variable from person to person, with no strong evidence to support blanket recommendations for changing your training based on cycle phase alone.
What does seem to help is paying attention to your own patterns. Some people find that lighter intensity or more recovery-focused sessions feel better in the days right before their period. Others notice no difference at all. Adjustments to sleep, nutrition, and training are most useful when tailored to what you actually experience rather than a rigid phase-based protocol. The higher calorie needs during this time do suggest that undereating before a workout may hit harder than it would in the first half of your cycle.
Tracking Your Luteal Phase
If your cycle is consistently around 28 days, the late luteal phase falls roughly during days 22 through 28. But cycles vary widely. A more reliable marker is counting backward: the luteal phase is relatively fixed at about 14 days, so the week before your period is the late luteal phase regardless of your total cycle length. Basal body temperature tracking can confirm when ovulation occurred, since the temperature shift marks the start of the luteal phase. Cycle tracking apps that log symptoms alongside dates can help you spot your personal pattern over two or three months, making it easier to anticipate and plan around your most symptomatic days.