The Shift

There are mornings where getting up feels heavier than it used to. The same inbox, the same meetings, the same responsibilities but the mental sharpness you once relied on has dulled somehow. You find yourself rereading emails and you have less patience for background noise. Even small requests feel disproportionately draining.

But you’re still showing up, keeping things moving, being where you’re needed and from the outside, very little appears to have changed. Internally however, the effort required to hold everything together has feels like it has increased.

In your twenties and thirties, there was a resilience you never questioned. You could push bedtime out past midnight or stay for another drink after work and still think clearly the next morning. You could skip a meal because the day ran away with you and not feel immediately shaky or unfocused. You could carry a heavier workload and rely on your drive and momentum to get you through it.

That momentum was driven, in part, by stress chemistry. Adrenaline and cortisol are designed to help you meet demand and used occasionally, they are adaptive but abused repeatedly, they become a pattern. Many women who have been functioning at a high level for years learn to operate in a near-constant state of sympathetic activation, the body’s “on” position. It can feel productive and sharp, like being slightly ahead of yourself, always leaning forward into the next task.

For years, the system was able to compensate creating a buffer. Oestrogen rose and fell in relatively predictable rhythms, supporting recovery, steadiness and forward drive. That buffering effect was subtle, effective and operating in the background.

Towards your late thirties and early forties your menstrual cycles naturally become less predictable and ovulation occurs less reliably. Oestrogen levels can fluctuate more noticeably, and the buffering effect lessens. The nervous system can no longer absorb the same level of chronic stimulation and what once felt sustainable begins to feel costly. The same workload that once energised you may now leave you wired at night or disproportionately depleted the following morning.

The shift begins through contrast. The contrast between the version of you that feels clear and capable and the version that feels thinner-skinned and more easily depleted becomes more noticeable but easy to dismiss at first.

Progesterone, the hormone produced after ovulation, is often the first to decline as cycles shift. It interacts with the brain’s primary calming pathway and supports mental steadiness. As ovulation becomes less consistent, that calming influence becomes less reliable.

When progesterone drops earlier in the cycle or fluctuates more, oestrogen may still rise and bring drive with it, but without the same stabilising influence from progesterone and a result your reactions can feel edgy, and irritation can arrive more quickly. A demanding day can spill into the next because the overnight reset feels less reliable.

At this stage, many women in their late thirties and forties interpret hormonal transition as personal decline when in reality it is the nervous system no longer tolerating override.

The contrast is not a sign that you are becoming less capable. It is a sign that the system is less willing to compensate.

What you are noticing reflects the cost of years of compressed sleep, skipped meals and running on drive.

You may find yourself thinking, “Why can’t I handle this like I used to?” The answer is not that you have weakened. It is that the strategy of pushing through is no longer as effective.

When you understand what is happening biologically, the internal narrative shifts. Instead of questioning your resilience, you begin to question your rhythm. That’s a very different starting point.

One of the first places this shift becomes visible is with your sleep.

This article is part of the Resilience Series.

Start here: When resilience changes.