Our Bodies Have Important Things To Say About Mental Health (& We’re Listening)

It’s been a rough day. Your heart feels like it’s going to jump out of your chest, your palms are sweaty, and your stomach hurts. You feel tired but also completely wound up. This is the mind-body connection at work, and while unpleasant, it’s the body’s way of signaling your mental load.

As Kristen Holmes, Ph.D., Principal Scientist at WHOOP and a psycho-physiologist, shared, “When you can pinpoint where things are going wrong for you, you can then understand where to start to apply your effort. We need to take stock of where things are going south, and usually, it’s things we can control.”

“Having this insight into your body helps you understand how to apply effort in a way that allows you to live your values more fully,” Holmes added. “It’s not about a higher score, it’s about having more energy, more joy—and getting control of your mental, physical, and emotional health is the path to that.”

HRV, or heart rate variability, refers to the time in between heartbeats. This may sound simple, but it’s an oh-so-individualized metric for understanding the state of stress within the body, your emotional resilience, and how to effectively manage both.

A higher HRV is a sign of greater adaptability to stress (and a longer lifespan1), showing the heart is efficient and agile. Lower HRV scores are linked to things like anxiety, heart disease, and even asthma. 

Psychologist and biofeedback expert Leah Lagos, Psy.D. shared why HRV is such a powerful tool for regulating mental health, “At its core, HRV reflects the adaptability of the autonomic nervous system—the body's way of shifting between states of calm and alertness. For many, HRV training translates into feeling more grounded and capable, even in the face of challenges. It empowers us to ‘reset’ during moments of tension, promoting a cycle of recovery and renewal that is essential for mental health.” 

There is no perfect HRV score for anyone, as it’s highly individualized. Tracking allows you to measure yourself against yourself, with gains signaling your stress management is heading in the right direction.

Holmes highlights the importance of noticing patterns over time, “If you see your HRV dropping over one, two, three weeks, it means the body literally isn’t adapting in a functional way to extra stress.” 

Lagos suggests approaching HRV optimization by identifying your “amplifiers” and “subtracters.” These will vary from person to person, but HRV amplifiers generally include exercise, time with loved ones, high-quality sleep, and stress reduction methods like meditation, while subtracters could be things like drinking alcohol, eating late at night, overworking, and sleep deprivation. 

The science is clear—when we lack adequate, high-quality sleep, brain activity changes for the worse, leading to difficulty making decisions and regulating emotions and behavior. We’ve all felt this, whether it’s an extra irritating day after a rough night or feeling unfocused and foggy. 

Sleep difficulties are a risk factor for depression, and vice versa, with 97% of depressed people struggling with poor sleep. Sleep deprivation is also linked to anxiety and neuroinflammation2, among other mental health concerns.

Elissa Epel, Ph.D., emphasized, “Poor sleep is one of the major pathways to depression, so monitoring sleep is important for both daily mood as well as preventing more serious health conditions.”

Holmes points out, “Both stress and anxiety are generally going to manifest in our sleep. I think wearables can be useful to understand what aspect of sleep you’re struggling with so you can seek the right kind of help. If you were to say, ‘I’m really struggling falling asleep,’ that’s very different from saying, ‘I’m constantly waking up at 2 a.m.’ These are different entry points for intervention.”

People have quickly caught on to the power of harnessing sleep data for personal health as the sleep monitoring apps market continues to grow rapidly. Valued at 3.94 billion in 2024, it’s expected to jump to 4.49 billion in 2025 and continue growing at 17.5% through 2037.

“Many wearable devices can detect correlations between our daily habits (like caffeine intake, late meals, or evening screen time) and sleep quality. For example, if stress leads to restless nights, seeing this reflected in a lower sleep score can drive targeted strategies for improvement. By identifying these patterns, we can make meaningful adjustments in daily routines, improving both sleep and mental well-being,” Lagos shared.

Because sleep tracking ratings vary between devices and use different metrics, we can’t distill this down to one range to work towards. Rather, we want to see improvements in patterns and identify the factors that support better quality sleep or steal from it. Things like going to bed too late, commonly experiencing racing thoughts, eating too late, bright light exposure, and lack of movement can all disrupt our sleep stages and bring mental health struggles along for the ride. 

On the other hand, an earlier bedtime, red light therapy, mouth tape, and a cooler bedroom may all help your scores soar. Of course, diet and lifestyle impact our sleep and mental health as well—what we do during the day has profound implications for the night.

By now we’ve all seen someone with a continuous glucose monitor (CGM) on their arm, and they’re usually telling everyone why it’s so great (it’s me, I’m this person). But there’s a reason for the excitement, especially if we want a more balanced mood and mental outlook.

“Metabolic health is intricately tied to mental health,” said Epel. “Relationships between stress, food intake, and glucose responses vary between people, but we have been studying stress eating for many years, and there are a few fundamental findings. If you are overweight, you are more at risk of having high stress levels and a negative mood. Mood affects eating and our levels of glucose and insulin on a daily basis,” she added.

Most people don’t recognize that dysregulated blood sugar levels can cause mood swings and wreak overall havoc on mental health. Insulin resistance doubles the risk of major depressive disorder, and people with high variability in blood glucose3 over time are more likely to develop anxiety and depression disorders. 

Add to that that the Western diet has a very high glycemic load—meaning a large impact in raising blood glucose—and by 2025, it’s expected that 100 million adults worldwide will have type 2 diabetes as a result.

“I really like the idea of these devices being used in concert with a professional to interpret the data correctly. It’s a matter of making sure you understand your motivation behind it and that you have the right kind of support to stay in a healthy range,” said Holmes. She added that for people with a history of eating disorders, CGMs have been found to be more harmful than beneficial. 

While we know certain foods are bound to raise blood glucose, like candy, white flour, and soda, glycemic responses can also vary widely when it comes to healthy foods, such as sweet potato. The beauty of CGMs is that we get a personalized look at how individual foods impact our glycemic response, and we can see a correlation between our mood and rises and falls in blood glucose. 

According to Holmes, the three core psychological needs of human beings are purpose, self-efficacy, and feeling in control. If our behaviors don’t align with our purpose, or we don’t feel like we have the resources to fulfill that purpose, it will manifest in our physiology. Using wearable data offers control over these seemingly abstract areas of life so we can see the link between our psychology and physiology and pivot accordingly.

In response to that growing awareness of the mind-body connection, the global fitness tracker market size is projected to grow 17.4% by 2033. With that, we’re likely to see new features that take personalized data even deeper. 

In addition to ever-evolving features on our beloved wearables like WHOOP and Oura, certain types of tech we may be hearing more about in terms of mental health include vibration devices that stimulate vagus nerve activity, like, for example, the Apollo bracelet, as well as microfluidic patches4 that can assess cortisol levels and other biomarkers in sweat, and even wearable biosensors to measure hydration.

“To me, the next frontier in really helping people with their mental health is getting a handle on sleep-wake timing, which means you need to get a handle on your light behavior during the day,” Holmes shared.