Half of the world’s population will undergo menopause if they live to middle age, but symptoms start occurring several years before that life change.

Many women start experiencing menopausal symptoms during those years of perimenopause, such as irregular periods, fatigue, sleep disturbances, hot flashes and weight gain.

Whereas many women used to deal with their symptoms alone, now more are talking about their symptoms with friends and on online support groups. They are trying to sort out exactly what perimenopause is and when it occurs. What are typical symptoms? Should women get their hormone levels checked? How can women manage perimenopausal weight gain? What if they have trouble sleeping? Where should people go for information — and what sources should they avoid?

To help us answer these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University. She previously served as Baltimore’s health commissioner.

CNN: What is perimenopause?

Dr. Leana Wen: Menopause is defined as the time in women’s lives when they stop having menstrual periods. Specifically, menopause occurs when 12 months have passed since menstrual periods have stopped.

For most women, periods don’t stop suddenly, although there are exceptions when menopause is induced by surgery or certain medical treatments that stop ovarian function. Instead, there is the transitional period of about four to eight years before menopause when levels of reproductive hormones are in flux. This time is known as perimenopause.

CNN: What age does it tend to occur?

Wen: Most women enter menopause in their 40s and 50s, with the average age being 52, according to the US Department of Health and Human Services’ Office on Women’s Health.

Perimenopause is the several years preceding menopause, so the most common age for women to begin perimenopause is in their 40s.

CNN: What are typical symptoms of perimenopause?

Wen: Irregular periods are one hallmark of perimenopause. The length of menstrual cycles may increase or decrease. The frequency also may change, and women may experience heavier or lighter periods than before. Periods may be skipped, and the time between them could lengthen by weeks or months, especially as women near menopause.

Hot flashes are another common manifestation of perimenopause. Night sweats can lead to sleep problems and accompanying brain fog during the day. Women also may experience mood swings due to fluctuating hormones and not getting enough sleep.

Some women experience vaginal dryness as estrogen levels diminish. This change can make sexual intercourse painful. Vaginal dryness also can increase the risk of urinary tract infections and urinary incontinence. Other symptoms can include dry skin, thinning of the hair and weight gain.

CNN: Should women get their hormone levels checked to see if they are in perimenopause? 

Wen: This is generally not recommended. First, menopause is a clinical diagnosis that’s made when someone has not had a period in the prior 12 months. There is no specific test that’s needed to diagnose menopause or perimenopause.

Second, testing may not yield a definitive answer. During perimenopause, hormone levels fluctuate a lot, and a test one day may look very different than one the next.

There are limited circumstances where testing could be beneficial. For example, someone who has had their uterus removed but not their ovaries won’t be menstruating. Also, women who are using hormonal birth control such as the oral contraceptive pill may not experience changes in menstruation, as their other symptoms could be masked by these hormones. They may want some way to see if they are reaching menopause. People under 40 who have stopped having periods may also want to be tested to see if they have something called premature ovarian failure, also known as primary ovarian insufficiency.

Other types of tests can be done, too. Just because someone is in the time in their life when they could be perimenopausal doesn’t mean that all their symptoms are due to hormone changes. It’s sometimes necessary to rule out other medical causes.

CNN: Does weight gain go along with perimenopause?

Wen: This is a real phenomenon. Part of the weight gain is due to aging and the slowing of metabolism and loss of muscle mass that comes with aging. The estrogen change during perimenopause also can lead to the redistribution of more body fat around the midsection. Lifestyle changes can play a role, too; stress, responsibilities of work and caregiving, and fatigue may lead to reduced physical activity or less attention to nutritious diets.

Some things can help with perimenopausal weight gain, starting with a diet that emphasizes whole foods like fruits, vegetables, nuts, meat, fish and whole grains. Try to decrease consumption of ultraprocessed foods, which are associated with obesity, diabetes, heart disease, cancer, dementia and a whole host of negative health outcomes. People who smoke should try to quit. And women should evaluate how much alcohol they are drinking, as it adds to excess calories.

Regular physical activity is also important. People who have primarily desk-based jobs should especially pay attention and work to incorporate short bursts of exercise throughout the day. The best exercise regimens are those that not only focus on cardio aerobic exercises but also incorporate weights for strength and resistance training. And prioritizing sleep is another key component, as consistent poor sleep is a risk factor for weight gain.

CNN: Speaking of sleep, what can be done for perimenopausal women who are having trouble sleeping?

Wen: It’s crucial to understand the underlying causes of poor sleep. Is it night sweats — are you also experiencing hot flashes doing the day? If so, treatments are available. Is it stress, depression and/or anxiety? Mental health issues also should be addressed. Otherwise, good sleep hygiene is always a great place to start — including establishing a sleep schedule, avoiding naps and alcohol, and stopping screen use in bed.

CNN: Is hormone treatment appropriate for women in perimenopause?

Wen: It’s important to distinguish between hormone therapy that is systemic, meaning it goes throughout the body, and therapy that contains hormones that target specific body parts.

For some women, systemic hormone treatment is appropriate. For instance, women who have substantial problems with hot flashes may benefit from it, which can come in the form of a pill, a patch, a spray and so forth. Individuals should discuss their symptoms and go over eligibility with their primary care provider.

CNN: What about other symptoms, such as vaginal dryness? Could that be alleviated with targeted hormone treatment?

Wen: Yes. There are a variety of vaginal tablets, creams and rings that can deliver estrogen directly to the vaginal tissue. They can help reduce vaginal dryness, pain with intercourse and some other urinary symptoms.

CNN: Where should people go for more information on perimenopause and menopause? And what sources should they avoid?

Wen: People who have a trusted primary care provider skilled at managing menopause patients should go to them. A resource I recommend highly is the The Menopause Society.

A number of companies sell products related to menopause and perimenopause. Some of them have useful information but use caution and recognize that they have commercial interests that may not always align with what is best for individual patients and their specific needs.

Another way to address the anxiety and stress that some women may experience is to lean on friends, both in person and virtually, who are going through this life change. These groups also can be a good way to share information, though, again, it’s important to make sure that the information can be traced back to reputable sources.