Perimenopause is the time period, which may last for months or years, leading up to menopause, during which your levels of the hormones estrogen, progesterone, and even testosterone begin to fluctuate and decline, signaling the approaching end of your reproductive ability. Menopause is reached once you’ve gone 12 consecutive months without a menstrual period. 

The fluctuation and decline of estrogen is the herald of perimenopause, and it can result in a wide variety of physical and cognitive symptoms, usually beginning in your mid-40s to mid-50s, though some people experience them earlier or later.

For those who still have their uterus, ovaries, and fallopian tubes, one of the more noticeable signs of perimenopause is irregular, unpredictable periods, in terms of both lightness or heaviness of flow, duration of periods, and the length of time between periods. You may even  miss a period completely, here and there. 

Those who still have their ovaries but no uterus, and who therefore no longer menstruate, will have to rely on other signs and symptoms as indications that they have entered perimenopause.

These can include:

• Hot flashes and night sweats, 
• Insufficient duration or quality of sleep,
• Mood swings, anxiety, or depression,
• Vaginal dryness, painful sex, and bladder issues,
• Skin and hair changes, and
• Health changes that affect your heart, bones, and other body parts.

Hot flashes and night sweats (hot flashes that occur while you sleep) are among the most recognizable perimenopause signs and symptoms, though they can also result from medications, certain health conditions, and consuming alcohol or spicy foods. Hormonal hot flashes are usually caused by the fluctuation and decline of natural estrogen levels in your body, signaling the first phase of the menopause journey.

Estrogen influences the hypothalamus, a gland in the brain that controls your body’s temperature, along with your appetite and sleep patterns. It also controls other hormones. Alternating levels of estrogen confuses the hypothalamus. 

Your heart may race, your blood vessels dilate, and blood rises to your skin’s surface, causing you to feel hot and start sweating. When it senses that you are too warm, it will initiate steps to cool you down. This can cause you to feel chilled right after a hot flash.

Approximately 50% of people in perimenopause experience sleep challenges. The decline of estrogen and progesterone, as well as the discomforts of night sweats, can also disrupt your sleep. You may find it difficult to get to sleep, stay asleep through the night, or get good quality sleep that enables you to wake feeling rested and refreshed. 

Chronic lack of adequate sleep can lead to daytime fatigue, irritability, and cognitive fuzziness, all of which can negatively impact your work and other daily activities, as well as your interpersonal relationships. It can also slow your reflexes and impair your judgement, making it potentially dangerous to drive or perform similar tasks.

Estrogen helps regulate serotonin, norepinephrine, and dopamine—hormones with mood-boosting properties. As estrogen fluctuates, so do these chemicals, resulting in changes in your brain that affect your mood. Estrogen also supports cognitive functions such as memory. 

Because of this, perimenopausal hormone fluctuations can lead to forgetfulness and fuzzy thinking, frustration, irritability, anxiety, and even depression. 

The decline of estrogen levels can also cause the loss of vaginal moisture and elasticity. This can lead to pain and the tearing of delicate vaginal tissue during sex, reduced sex drive, and bladder issues such as incontinence.

Other physical changes that you may notice include changes to your skin and hair. Estrogen loss leads to collagen loss, and collagen supports and nourishes hair and skin. Your skin may become drier, thinner, start to look “crepey”. You might see acne on your face. Hair on your head may grow thinner and become more sparse. 

Estrogen affects multiple body systems, and not all signs and symptoms of perimenopause are noticeable without blood or other lab tests. Some other health effects to watch out for include:

• Decreased fertility. The loss of estrogen causes your ovulation—and therefore your periods—to grow irregular, and therefore more difficult to predict if you’re trying to get pregnant. If you’re still having periods, however, you can still get pregnant.
• Bone loss. Though you won’t feel it happening, lower estrogen levels also mean that you start to lose bone minerals faster than your body can replace them, making your bones thinner, weaker, and more prone to fractures and breaks.
• Heart health challenges. Estrogen loss can also lead to unwelcome changes in your heart health. When you visit the doctor, you might find that your cholesterol, blood pressure, and, subsequently, your risk for heart disease have increased. You may also notice heart palpitations, though that’s usually temporary during perimenopause.