Why Do Hot Flashes Cause Insomnia? (Research Summary)

There is a strong association between hot flashes and sleep issues. We’ll look at research that shows this connection in this short post.

Note that while hot flashes are most commonly associated with menopause, there are other potential causes like radiochemotherapy (1).

Not surprisingly, hot flashes are a sleep disturbance that disproportionately affects women. Women in general have a much greater risk of developing sleep issues (e.g. from periods, pregnancy, hysterectomy).

How Often Do Hot Flashes Cause Insomnia?

The first study that we’ll look at together had a sample of 982 middle aged women between the ages of 35 and 65. In short, they sorted them into menopausal stages, recorded the severity of hot flashes they experienced, as well as their sleep quality (2).

The overall conclusion was clear:

Severe hot flashes are strongly associated with chronic insomnia in midlife women... Treating hot flashes could improve sleep quality and minimize the deleterious consequences of chronic insomnia.

Let’s start with how many women get hot flashes?

There were 3 main categories considered:

• Mild - A heat sensation, but no sweating.
• Moderate - A heat sensation and some sweating.
• Severe - Enough sweating and heat to cause a woman to stop an activity.

It’s clear that women going through menopause are much more likely to have all types of hot flashes.

Even in postmenopause, almost 40% of women have some degree of hot flashes on a regular basis.

While any degree of hot flash can affect sleep, 81.3% of women with severe hot flashes had chronic insomnia symptoms. That is a very strong correlation.

Hot Flashes Aren’t the Only Cause of Insomnia in Aging Women

So case closed right?

Not quite.

As we’ll see shortly, treating hot flashes alone doesn’t always help someone achieve “good” sleep quality.

In other words, hot flashes are one cause of insomnia, but not the only one. 

The study also looked at the sleep quality of women who didn’t experience hot flashes, and found that a large degree of them had chronic insomnia, and only some percent of that was explained by menopause.

The image above shows the breakdown of results. While it varies, menopause only explained about half of the overall number of insomnia cases in this cohort of 982 women.

So while treating hot flashes is important (arguably the most important), physicians need to look at treating other factors in aging women that lead to insomnia.

SummaryA majority of women will experience hot flashes for at least a period of their lives, and a majority of those women will develop chronic insomnia. However, aging women have a high risk of developing insomnia regardless of if they experience hot flashes. Therefore, sleep treatment should focus on not only treating the hot flashes, but also other causes.

Why Do Hot Flashes Cause Insomnia?

Hot flashes are one of the more obvious causes of sleep trouble.

Both heat and potentially night sweats cause most people to be more aroused, which either causes difficulty maintaining sleep, or lowers the quality of it (i.e. frequent wakeups, light sleep).

But heat isn’t the only problem.

Post-menopausal women with hot flashes often exerience chronic pain as well. This chronic pain can make it difficult to sleep.

In addition, while a hot flash alone might lead to short term sleep disturbances, but can also lead to sleep disorders like chronic insomnia.

The domino hypothesis is the most likely current explanation (3). It proposes that hot flashes cause short term sleep issues, which leads to a greater risk of other health problems like anxiety and depression (mental health disorders are strongly linked to insomnia) that further worsen sleep trouble.

SummaryHot flashes cause discomfort that makes it more difficult to sleep well, which can then lead to other problems that contribute to developing chronic insomnia, which can lead to overall poor health.

Treatment Options for Hot Flashes and Insomnia

When it comes to sleep problems, it’s very easy to get trapped in a vicious cycle of one symptom leading to another, and even if you treat the first root cause, it doesn’t always fix the rest.

That’s why it’s important to take insomnia seriously when symptoms first arise, and to see a doctor for help with devising a treatment plan.

A comprehensive approach is needed to treat insomnia, even in the specific case of hot flashes. Let’s look at some research that clearly shows that.

There are a few different ways that insomnia is usually treated:

• Cognitive behavioral therapy for insomnia (CBTi) - Typically this is the best treatment for most cases of insomnia, including women with menopausal symptoms. It teaches you to reframe thoughts causing anxiety and sleep issues, among other things.
• Medication - There are many medication options for sleep trouble. They take effect right away and are obviously convenient, but they don’t always have a huge effect and can come with side effects. Some common sleep medicine studied for women with hot flashes and insomnia are escitalopram, eszopiclone, estradiol, and venlafaxine (4,5,6).
• Relaxation therapy - In insomnia cases driven by anxiety, research shows that relaxing things like yoga, meditation, and acupuncture can help insomnia.

If it's clear that all sleep issues stem from menopause symptoms, hormone therapy is also a potential treatment option.

Again, if you’re actually suffering from insomnia, your doctor will help you put together a specific plan.

What’s the Most Effective Treatment Option?

One study compared multiple treatment options in women with hot flashes (7). They used the PSQI scale, where a lower score is better to measure the results (see our PSQI online calculator if you’d like to learn more).

The graph below shows the change in PSQI during the intervention period (reminder: lower score over time is good).

The only treatment methods specifically targeting the hot flashes were the medications (escitalopram, estradiol, and venlafaxine).

While those medications produced a significant improvement in PSQI score (just over -1 averaged), CBTi produced the greatest improvement in sleep quality by a significant amount.

That’s an interesting finding that really confirms that hot flashes are just one of the reasons that aging women experience such a high risk of developing sleep disorders like insomnia. 

Note that even adding exercise or yoga had a significant positive effect as well (comparable to the medications).

While this study didn’t look at combining treatment options (e.g. medication plus CBT), that may produce even better results. It’s an option that doctors can consider with their patients depending on the specific circumstances.

Finally, it's possible that sleep medication is most effective in cases where severe hot flashes cause trouble sleeping, while therapies like CBT are better for more minor cases.

References

1. Fatigue, insomnia and hot flashes after definitive radiochemotherapy and image-guided adaptive brachytherapy for locally advanced cervical cancer
2. Severe Hot Flashes Are Associated With Chronic Insomnia
3. Insomnia and hot flashes
4. Effect of Escitalopram on Insomnia Symptoms and Subjective Sleep Quality in Healthy Menopausal Women with Hot Flashes
5. Eszopiclone improves insomnia and depressive and anxious symptoms in perimenopausal and postmenopausal women with hot flashes: a randomized, double-blinded, placebo-controlled crossover trial
6. Effects of Estradiol and Venlafaxine on Insomnia Symptoms and Sleep Quality in Women with Hot Flashes
7. Effects of Pharmacologic and Nonpharmacologic Interventions on Insomnia Symptoms and Self-reported Sleep Quality in Women With Hot Flashes