Night Sweats and Mood Swings? Perimenopause

Medically reviewed by Dr. William Aung, DocDocDash’s partner doctor network.
Last reviewed: October 2026.

You wake at 3am with damp sheets and a racing mind, kick off the blanket, then lie awake until the alarm. The next day you are tired, short-tempered over small things, and a little foggy. Meanwhile your period has been arriving early, late, or heavier than usual, and you wonder whether it is stress, your thyroid, or simply too much on your plate. For many women in their 40s, and sometimes in their late 30s, there is another explanation worth knowing about: perimenopause.

Quick answer: Night sweats, mood swings, low energy, and changing periods are common early signs of perimenopause, the years of transition before menopause when estrogen and progesterone levels begin to rise and fall unpredictably. It usually starts in the 40s but can begin earlier. Because thyroid problems, low iron, and stress cause similar symptoms, a doctor’s check and a few blood tests can confirm what is behind them.

Can Low Energy, Mood Swings, and Changing Periods Be Early Signs of Perimenopause?

Yes. “Perimenopause” means “around menopause.” During this stage your ovaries make hormones less predictable. Estrogen does not simply drift down. It can swing high and low from month to month, and those swings cause many of the symptoms. Menopause itself is confirmed after 12 months without a period, which happens in the early 50s on average. Perimenopause often lasts around four years, and sometimes longer.

Common signs include:

Periods that become shorter, longer, heavier, lighter, or skipped
Hot flashes and night sweats
Trouble falling or staying asleep
Irritability, anxiety, or low mood
Brain fog and forgetfulness
Vaginal dryness and lower sex drive
Aching joints and tiredness

Symptoms vary a great deal between women, and not everyone gets hot flashes. Broken sleep from night sweats can make mood and concentration worse, which is why the symptoms feed each other.

What Else Can Look Like Perimenopause?

Several treatable conditions cause the same symptoms, so it is worth ruling them out:

An underactive or overactive thyroid
Iron deficiency or anemia
Low vitamin D or vitamin B12
PCOS or other hormonal conditions
Pregnancy
Depression, anxiety, or sleep apnea
Some medicines

Which Tests Should I Ask For If I Think It’s Perimenopause?

There is no single test that confirms perimenopause. Hormone levels such as FSH and estradiol change from day to day, so one “normal” result does not rule it out, and many guidelines do not recommend routine hormone testing for women over 45 with typical symptoms. Doctors mainly use your age, symptoms, and cycle pattern, and order tests to rule out other causes:

Pregnancy test, if your period is late
TSH (thyroid function)
Complete blood count and ferritin (iron stores)
Vitamin D and vitamin B12
HbA1c and cholesterol, since heart and metabolic risk rise around menopause

Hormone tests may be considered if you are under 45 or your symptoms are unusual. DocDocDash’s perimenopause and women’s hormonal health packages bundle these tests.

How Is Perimenopause Managed?

Lifestyle steps help many women: regular exercise including strength training, a cool bedroom, a steady sleep routine, and cutting back on alcohol or caffeine if they trigger hot flashes. Cognitive behavioral therapy (CBT) also has good evidence for easing hot flashes and low mood.

Menopausal hormone therapy is the most effective treatment for hot flashes and night sweats. For many healthy women starting around the time of menopause, the benefits outweigh the risks, but it is not right for everyone, for example some women with a history of breast cancer or blood clots. Non-hormonal medicines also exist. Please talk to a doctor before taking over-the-counter “menopause supplements,” since their quality varies.

One more point: you can still get pregnant during perimenopause. Keep using contraception until a doctor confirms you have reached menopause.

When Should I See a Doctor Instead of Waiting?

Get checked promptly if you have very heavy bleeding (soaking a pad or tampon every hour for several hours), bleeding between periods or after sex, periods that come less than 21 days apart, any bleeding after 12 months without a period, chest pain, or severe low mood or thoughts of harming yourself.

Frequently Asked Questions

At what age does perimenopause start?
It usually starts in the mid-40s, but some women notice changes in their late 30s or early 40s. It can last several years before periods stop for good.

Can I still get pregnant during perimenopause?
Yes. Ovulation becomes irregular but does not stop, so contraception is still needed until a doctor confirms menopause.

Is there a single test that confirms perimenopause?
No. Hormone levels fluctuate, so doctors rely mainly on your age, symptoms, and cycle changes, and use blood tests mostly to rule out other causes.

A Simple Rule to Carry Forward

Night sweats and mood swings are not “just stress” until other causes have been checked. Track your cycle and symptoms for two to three months, then take that record to your doctor.

Ready to take the next step? DocDocDash can help you find hospitals or clinics offering perimenopause and hormonal health screening, compare what each package includes, and book a consultation, all in one place.

Sources: World Health Organization, “Menopause” fact sheet; National Institute for Health and Care Excellence (NICE), guideline NG23, “Menopause: identification and management”; Harlow SD et al., “Executive summary of the Stages of Reproductive Aging Workshop + 10,” Menopause (2012).