A quiet exhaustion that deserves understanding
If you are moving through perimenopause and feeling unusually tired, flat, or low on energy, you are not imagining it. This kind of fatigue can feel different from normal tiredness. It may show up as early evening exhaustion, heavy limbs, brain fog, or a sense that your internal battery simply does not recharge the way it used to. Many women describe it as doing less yet feeling more depleted.
This experience is extremely common. It is not a personal failure, a lack of discipline, or a sign that something is wrong with your character. Perimenopausal fatigue reflects real, measurable changes in hormones, brain signalling, and nervous system sensitivity. Naming it matters, because understanding what is happening can soften self-blame and open the door to more supportive choices.
The shifting biology behind low energy
Perimenopause is a time of fluctuation rather than steady decline. Oestrogen and progesterone rise and fall unpredictably, sometimes within the same week. These hormones are not just involved in reproduction; they also influence how cells make energy, how blood sugar is regulated, and how efficiently oxygen is used in muscles.
Oestrogen, in particular, plays a role in mitochondrial function, the process by which cells produce energy. When oestrogen levels swing, energy production can feel less reliable. Some days you may feel almost normal, while on others even simple tasks feel disproportionately draining.
Progesterone adds another layer. It has a naturally calming effect on the brain and nervous system. When progesterone drops or becomes inconsistent, the brain can experience more background “noise,” meaning it works harder to stay regulated. That extra effort consumes energy, even if nothing obvious has changed in your day.
The brain’s role in perimenopausal fatigue
The brain is both an energy-intensive organ and one that is highly sensitive to hormonal change. During perimenopause, areas involved in temperature regulation, sleep–wake cycles, mood, and attention all receive different hormonal signals than they did before.
This can lead to a subtle but important shift: the brain may spend more time in a state of vigilance. Even without conscious anxiety, the nervous system can become more reactive. When the brain stays on alert, the body diverts resources toward monitoring and coping instead of restoration.
Over time, this neurological “background load” can feel like mental fatigue, reduced motivation, or difficulty sustaining focus. It is not laziness. It is a brain adapting to changing chemistry while trying to keep you functioning.
Why energy often dips at night
Many women notice that fatigue and low energy feel more pronounced in the evening or overnight. This pattern has biological roots. Oestrogen supports the production and regulation of melatonin, the hormone that guides sleep timing and quality. When oestrogen fluctuates, melatonin rhythms can become less predictable.
At night, when the day’s demands finally slow, the nervous system may reveal how taxed it has been. What felt manageable during daylight can surface as deep exhaustion, restlessness, or difficulty winding down. For some, the body feels wired but tired at the same time.
This is also when cortisol, the body’s primary stress hormone, can become dysregulated. Instead of tapering smoothly in the evening, cortisol may stay elevated or spike overnight. That internal mismatch often contributes to unrefreshing sleep and next-day fatigue.
Factors that can quietly amplify fatigue
Perimenopausal fatigue rarely exists in isolation. Modern life places significant demands on the nervous system, and hormonal fluctuations can reduce resilience to those demands.
Chronic stress, even when familiar, uses up mental and physical energy. Sleep debt accumulates more quickly during this stage of life, and the body may recover more slowly from late nights or interrupted rest. Alcohol can temporarily feel relaxing but may interfere with deep sleep and overnight nervous system recovery.
Highly structured or high-output lifestyles, especially those that worked well earlier in adulthood, may suddenly feel unsustainable. This does not mean you are doing something wrong. It often means your internal thresholds have changed, even if your external expectations have not.
What many women find genuinely supportive
Across many experiences, certain themes tend to help women feel more steady over time. These are not quick fixes or rigid rules, but patterns that seem to work alongside a fluctuating system rather than against it.
First, predictability can be soothing. Regular rhythms around meals, movement, and rest give the nervous system a sense of safety. When the body senses consistency, it often expends less energy on internal regulation.
Second, gentler forms of physical activity often feel more sustainable than extremes. Movement that supports circulation and mood without overwhelming the system can leave women feeling more energised rather than depleted.
Third, emotional regulation becomes just as important as physical rest. Practices that reduce mental overstimulation and allow for psychological unwinding can lower the background energy drain created by constant alertness.
Finally, many women benefit from adjusting expectations. Energy may now fluctuate day to day rather than follow a predictable curve. Working with that variability, rather than fighting it, can reduce frustration and preserve energy.
A gentler way forward with less self-judgment
Perimenopausal fatigue and low energy are signals, not defects. They reflect a body and brain in transition, recalibrating systems that have functioned one way for decades. That recalibration takes resources.
A gentler way forward begins with permission to believe what your body is telling you. It involves replacing self-criticism with curiosity and recognising that rest, pacing, and emotional support are not indulgences at this stage of life, but forms of respect.
Energy during perimenopause may not look the same as it did before. Yet many women discover a deeper, more sustainable rhythm on the other side of this transition. One that values steadiness over speed and attunement over pushing through.
You are not alone in this experience, and you are not failing. Your system is doing complex work behind the scenes. Meeting that work with understanding rather than resistance can itself become a quiet source of energy.
