If you ask the average person when perimenopause starts, they will likely guess age 50. If you ask a woman in her late 30s, she will likely say, “Not me, I’m too young.”
Both are wrong. If you are waiting for your 50s to pay attention to your hormones, you are looking at the wrong mile marker. The physiological shifts of the transition actually begin as early as age 35. This is what medical professionals call the “Late Reproductive Phase,” but for you, it might just feel like suddenly not being able to tolerate that second glass of wine or needing an extra hour of sleep to function.
The Invisible Decline: Progesterone vs. Estrogen
The reason we miss the starting gun is that we associate menopause with a lack of Estrogen. Estrogen is the famous hormone; when it leaves, you get hot flashes and stop having periods. But Estrogen is the last one to leave the party.
At age 35, the first domino to fall is Progesterone. Progesterone is produced by the corpus luteum (the shell of the egg) after you ovulate. As your ovaries age, your ovulation becomes less robust. You produce less progesterone.
Why does this matter? Progesterone is nature’s Valium. It is a soothing, calming, anti-anxiety hormone. It promotes deep sleep and reduces inflammation. When it begins its slow, silent decline in your mid-30s, you don’t get hot flashes. You get insomnia. You get anxious. You get PMS that feels a little more jagged than it used to.
The Symptom Mismatch
Because Estrogen levels are still normal (or even high) at 35, you still have regular periods. This tricks you into thinking everything is fine. But the ratio between Estrogen and Progesterone is drifting apart. This is “Estrogen Dominance” (or Progesterone Deficiency).
The symptoms of Mile Marker 35 are rarely gynecological. They are usually:
- Alcohol Intolerance: Hangovers from one drink.
- Sleep Maintenance Issues: Waking up at 3 AM.
- Weight Distribution: A slight thickening around the middle that diet doesn’t fix.
- Mood Instability: Feeling overwhelmed by tasks that you used to juggle easily.
The “Just Aging” Trap
The danger of Mile Marker 35 is dismissal. Because these symptoms are subtle and common, we write them off. We tell ourselves, “I’m just getting older,” or “I’m just stressed because of the kids/job.”
Acknowledging that the transition starts now isn’t about feeling “old.” It’s about strategic intervention. If you recognize that your sleep issues are hormonal, you can treat them with magnesium or sleep hygiene rather than sleeping pills. If you recognize that your anxiety is linked to progesterone loss, you can support your body with Vitamin B6 and stress reduction.
Preparing for the 40s
Think of age 35 to 40 as the “Pre-Game.” The game isn’t in full swing yet, but you need to start taping your ankles and hydrating.
This is the time to clean up your lifestyle. The body that forgave you for all-nighters and junk food in your 20s will stop forgiving you now. The liver has to work harder to metabolize excess hormones. The adrenal glands have to work harder to manage stress.
If you ignore Mile Marker 35, you risk crashing into Mile Marker 45. But if you pay attention now, you can flatten the curve of the transition.