Half of the world’s population will be in menopause by the time they reach middle age, but symptoms begin to appear several years before this life change.

Many women begin to experience menopausal symptoms during these perimenopausal years, such as irregular periods, fatigue, trouble sleeping, hot flashes, and weight gain.

While many women managed their symptoms on their own, more are now talking about them with friends and in online support groups. They are trying to understand exactly what perimenopause is and when it occurs. What are the typical symptoms? Should women have their hormone levels checked? How can women manage weight gain during perimenopause? What if they have trouble sleeping? Where should people go for information – and which 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 period in a woman’s life when she stops having her period. More specifically, menopause occurs when 12 months have passed since menstruation stopped.

For most women, periods do not stop suddenly, although there are exceptions when menopause is induced by surgery or by certain medical treatments that stop ovarian function. Instead, there is a transition period of about four to eight years before menopause, when reproductive hormone levels fluctuate. This period is known as perimenopause.

CNN: At what age does this usually happen?

Magnifying glass: Most women enter menopause between the ages of 40 and 50, with the average age being 52, according to the U.S. Department of Health and Human Services. Office of Women’s Health.

Perimenopause corresponds to the years preceding menopause. So the most common age at which women begin perimenopause is in their 40s.

CNN: What are the typical symptoms of perimenopause?

Magnifying glass: Irregular periods are a punch of perimenopause. The length of menstrual cycles may increase or decrease. The frequency may also change and women may have heavier or lighter periods than before. Periods may be missed and the time between them may extend by several weeks or months, particularly as women approach menopause.

Hot flashes are another common manifestation of perimenopause. Night sweats can lead to sleep problems and brain fog during the day. Women may also experience mood swings due to hormonal fluctuations and lack of sleep.

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

CNN: Should women have their hormone levels checked to see if they are perimenopausal?

Magnifying glass: This is generally not recommended. First, menopause is a clinical diagnosis made when a person has not had a period in the previous 12 months. No specific tests are needed to diagnose menopause or perimenopause.

Second, the tests may not give a definitive answer. During perimenopause, hormone levels fluctuate a lot and one day’s test can be very different from the next.

There are limited circumstances in which testing might be beneficial. For example, a person who has had their uterus removed but not their ovaries will not have their period. Additionally, women who use a hormonal birth control method such as the oral contraceptive pill may not experience changes in their periods because their other symptoms might be masked by these hormones. They may want to find a way to see if they reach menopause. People under 40 who have stopped menstruating may also want to get a test to see if they have what is called premature ovarian failure, also known as primary ovarian failure.

Other types of tests can also be performed. Just because a person is at a point in their life where they might be in perimenopause doesn’t mean all of their symptoms are due to hormonal changes. It is sometimes necessary to exclude other medical causes.

CNN: Does weight gain accompany perimenopause?

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

There are a few things that 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 reduce your consumption of ultraprocessed foodswhich are associated with obesity, diabetes, heart disease, cancerdementia and a range of negative health consequences. People who smoke should try to quit. And women should evaluate the amount of alcohol they drink, as it adds to excess calories.

Regular physical activity is also important. People who have mainly office jobs should especially pay attention and strive to incorporate short bursts of exercise throughout the day. The best exercise programs are those that don’t just focus on cardio-aerobic exercises but also incorporate weights to strength and resistance training. And prioritizing sleep is another key, as consistent poor sleep is a risk factor for weight gain.

CNN: Speaking of sleep, what can we do for perimenopausal women who have trouble sleeping?

Magnifying glass: It is crucial to understand the underlying causes of poor sleep. Is it night sweats? Do you also have hot flashes during the day? If applicable, treatments are available. Is it stress, depression and/or anxiety? Mental health issues also need to be addressed. Otherwise, good sleep hygiene is always a good place to start, including establishing a sleep schedule, avoiding naps and alcohol, and stopping using screens in bed.

CNN: Is hormone therapy appropriate for perimenopausal women?

Magnifying glass: It is important to distinguish between systemic hormone therapy, meaning it applies to the entire body, and therapy that contains hormones that target specific parts of the body.

For some women, systemic hormonal treatment is appropriate. For example, women who have significant problems with hot flashes can benefit from it, in the form of a pill, patch, spray, etc. Individuals should discuss their symptoms and verify eligibility with their primary care provider.

CNN: What about other symptoms, like vaginal dryness? Could this be alleviated by targeted hormonal treatment?

Magnifying glass: Yes. There are a variety of tablets, creams, and vaginal rings that can deliver estrogen directly to the vaginal tissues. They can help reduce vaginal dryness, pain during sex, and some other urinary symptoms.

CNN: Where should you go for more information about perimenopause and menopause? And which sources should they avoid?

Magnifying glass: Those who have a trusted primary care provider knowledgeable in the care of postmenopausal patients should reach out to them. One resource I highly recommend is The Menopause Society.

A number of companies sell products related to menopause and perimenopause. Some of them have useful information, but are cautious and recognize that they have commercial interests that do not always align with what is best for each patient and their specific needs.

Another way to cope with the anxiety and stress some women may feel is to lean on friends, in person and virtually, who are going through this life change. These groups can also be a good way to share information, although, again, it is important to ensure that information can be traced back to reliable sources.