Tag Archives: Cortisol

New, wearable cortisol sensor can help warn us of incoming burnout or depression

It’s no secret that life can get rough. Those who have to contend with that for too long can start feeling overwhelmed — burned out by the stress. Now, a team of researchers proposes a new approach through which we can quantify how much stress someone is under, and for how long. They hope that the new wearable device can help prevent burnout, and let us know when someone is most in need of support or a good old fashioned break from the stress.

Image via Pixabay.

The new device was designed by a team of engineers at Ecole Polytechnique Fédérale de Lausanne (EPFL) Nanoelectronic Devices Laboratory (Nanolab) and Xsensio, a Swiss-based biotech company. It takes the shape of a wearable sensor that measures the levels of stress hormone cortisol in a person’s sweat. This figure can then be used to gauge the levels of cortisol in the blood.

The sensor is placed directly on the skin and provides continuous readings of this hormone’s levels in their sweat.

Skin-deep stress

“Cortisol can be secreted on impulse — you feel fine and suddenly something happens that puts you under stress, and your body starts producing more of the hormone,” says Adrian Ionescu, head of Nanolab.

“But in people who suffer from stress-related diseases, this circadian rhythm is completely thrown off. If the body makes too much or not enough cortisol, that can seriously damage an individual’s health, potentially leading to obesity, cardiovascular disease, depression or burnout.”

Cortisol is synthesized from cholesterol in our body’s adrenal glands — these sit right on top of your kidneys. How much of it is secreted is in turn controlled by the pituitary gland in our brains through the use of the adrenocorticotropic hormone (ACTH).

It’s easy to read “stress hormone” and immediately assume cortisol is a bad guy, but that’s simply not true. As we’ve seen previously, stress is a completely natural and deeply useful response; the issue with it today is that we’re feeling much more stress than we would in our natural environment. In other words, stress isn’t the issue — too much stress, is.

In our day-to-day, cortisol has some very important functions, including keeping our metabolism, blood sugar, and blood pressure in check. It’s also deeply involved in other cardiovascular functions and the workings of the immune system. In a stressful situation, be it something life-threatening or a simple annoyance, cortisol is flooded into the body to make us ready for our ‘fight or flight’. This mostly means prepping up our brain, muscles, and heart for intense activity and possible injury.

Still, cortisol levels in the blood ebb and flow naturally throughout the day, following our circadian rhythm, to keep us functional or asleep as needed. It generally peaks between 6 am and 8 am to rouse us from sleep and then decreases gradually.

Since cortisol is such a good marker for how stressed we feel and how stressed our body actually is, it’s often used as a gold standard to gauge stress. To do that however you need a blood sample, and those aren’t something you can take just anywhere throughout your day.

That’s why the team designed a wearable sensor to measure how much cortisol an individual excretes through their skin. It contains a transistor and a graphene electrode, which the authors explain has very high sensitivity and can detect even low levels of the hormone. Aptamers, short fragments of single-stranded DNA or RNA that can bind to specific compounds, are tied to this graphene electrode, allowing it to interact with the cortisol molecule. Since the aptamers used naturally contain a negative charge, they will be electrostatically attracted to the cortisol molecule and release a charge as they bind together.

The more such molecules are present, the stronger the overall charge becomes. This allows for an accurate and direct measurement of its levels in sweat. The authors explain that this is the first device intended to continuously monitor cortisol levels throughout the circadian cycle (i.e. throughout the day).

“That’s the key advantage and innovative feature of our device. Because it can be worn, scientists can collect quantitative, objective data on certain stress-related diseases. And they can do so in a non-invasive, precise and instantaneous manner over the full range of cortisol concentrations in human sweat,” adds Ionescu.

They tested the device in the lab and found it reliable and efficient; the next step is to now make it available for healthcare workers or researchers. They’ve set up a bridge project with Prof. Nelly Pitteloud, chief of endocrinology, diabetes, and metabolism at the Lausanne University Hospital (CHUV), where the device will be tested for continuous use in a real-life hospital setting. They intend to run the test using healthy individuals as well as patients with Cushing’s syndrome (who produce too much cortisol), Addison’s disease (too little cortisol), and stress-related obesity.

As far as the psychological ramifications of stress, the team explains that they are still “assessed based only on patients’ perceptions and states of mind, which are often subjective”. A system such as this patch can help us determine quite reliably how much cortisol is running through their system, which can be used to gauge those at risk of depression or burnout. If nothing else, it will help them support their claims with cold-hard figures.

The paper “Extended gate field-effect-transistor for sensing cortisol stress hormone” has been published in the journal Communications Materials.


Smiles can both induce and reduce stress — it depends on how you wield it

New research finds that smiles can be used to both soothe or attack — at least, as far as the brain’s stress pathways are concerned.


Image via Pixabay.

A faltering voice. A racing heart. Sweaty palms. Those are some of the symptoms of stress that we’ve all experienced at one time or another — during an exam, before an exciting date, before speaking in public. We know that such events can instill stress even in the most level-headed out there, but new research shows that a single smile can also have the same effect — if done well.

The study, published by researchers from the University of Wisconsin-Madison and Bar-Ilan University, looked at the interaction between nonverbal feedback and the activity of the hypothalamic-pituitary-adrenal (HPA) axis, our body’s central stress response system.

We know that verbal feedback, such as telling someone “that was/wasn’t good” following a speech can influence the activity of the HPA axis, either determining a rise or a lowering of stress-hormone cortisol. However, there was very little scientific research looking into how our HPA axis responds to purely nonverbal feedback, such as facial expressions.

Turns out your brain is actually paying a lot of attention to all of these cues. The team reports that smiles can reduce or increase physical stress, depending on how they are perceived. They also showed that smiles with different social functions have different effects on the HPA axis, when perceived as feedback in the context stressful social situations.

For the study, the team worked with 90 male undergrad students, using the cortisol levels in their saliva as a measure of their HPA activity. They report that ‘dominance’ smiles, those smirky things we use to convey disapproval or to challenge social standings, were associated with higher HPA axis activity — this type of smile correlated to an increase in heart rates and levels of cortisol in the participants’ saliva. Those who perceived ‘dominance’ smiles also needed a longer period to return to their baseline cortisol levels after experiencing a stressful event. All in all, the team notes, the physical responses to dominance smiles mirror the effect of negative verbal feedback on the HPA axis.

On the other hand, ‘reward’ and ‘affiliation’ smiles — which reinforce behavior, grease social wheels, or are meant to signal the lack of threats — have an effect similar to displays of friendliness or positive verbal feedback on the HPA axis, lowering the participants’ stress and improving their psychological resilience to stress.

Types of smiles.

Reward smiles (left) reinforce desired behavior by signaling positive feelings; affiliation smiles (center) promote approachability by signaling non-threat; dominance smiles (right) influence social hierarchies by signaling superiority.
Image credits Jared D. Martin, Magdalena Rychlowska.

The authors further report that individuals with higher heart-rate variability (the variation in time between heartbeats) showed the widest range of responses to different smiles. Higher heart rate variability has previously been correlated with a higher ability to recognize facial expressions.

“The findings provide further evidence for the view that smiles do not necessarily constitute positive nonverbal feedback, and that they may impact social interactions by affecting the physiological reaction of people who perceive them,” the authors write.

“In addition, cortisol appears to support the detection of social threat and coordinate biological activity needed to adequately respond to the threat.”

The findings help patch in our understanding of the depth of nonverbal communication in human language — as a tool to unnerve, a hand to soothe, and as an outside effect on our psychological state. However, the team cautions that because of the small sample of exclusively male participants, the findings shouldn’t be generalized until replicated. Thus, further research will need to explore whether or not men and women react differently to the same kind of smile, and to test more overt (both negative and positive) facial expressions.

The paper ” Functionally distinct smiles elicit different physiological responses in an evaluative context” has been published in the journal Scientific Reports.

Smelling your partner’s shirt will reduce stress, but a stranger’s will wind you up more

Women feel calmer after being exposed to their male partner’s scent, new research has found. The improvement was observable in their cortisol levels during mock stress trials.


Image credits Alterio Felines.

Smell is a powerful driver of emotion and memory. Just a whiff of something your parents used to cook is enough to yank you back to your childhood days, and a hint of a lover’s perfume enough to put the spring back in your step. New research shows that smell can also be a very powerful weapon against stress. The scent of your partner can help lower levels of the stress hormone cortisol even when they’re not there. But beware — the scent of a stranger had the opposite effect.

Benefits you can smell

Authors recruited 96 opposite-sex couples for their study. Men were given a clean t-shirt and told to wear it for 24 hours. They were asked not to use deodorant or other scented body products during this time and refrain from smoking and eating certain foods which might influence their scent during this time. The garments were frozen after being worn to preserve the scent.

The women were then randomly assigned to smell a t-shirt that was either unworn, worn by their partner, or one worn by a stranger, without being told which they were given. Afterwards, they underwent a stress test in the form of a mock job interview and a mental math task. Finally, they filled in a questionnaire regarding their stress levels and saliva samples were taken to measure their cortisol levels. The team asked the ladies to sniff-test the t-shirts because they tend to have a better sense of smell than men.

Overall, women who had smelled their partner’s shirt felt less stressed — both before and after the interview and math tests. Interestingly, those who both smelled their partner’s shirt and correctly identified who it belonged to, showed the lowest average cortisol levels among all the participants. This latter finding suggests that the stress-reducing benefits are most pronounced when women are also consciously aware of what they’re smelling.

“Many people wear their partner’s shirt or sleep on their partner’s side of the bed when their partner is away, but may not realize why they engage in these behaviours,” said lead author Marlise Hofer from the University of British Colombia.

“Our findings suggest that a partner’s scent alone, even without their physical presence, can be a powerful tool to help reduce stress.”

On the other hand, women who received and smelled a stranger’s scent showed higher average cortisol levels throughout all steps of the test.

The authors believe that this effect is tied to old evolutionary pressures. Hofer says that humans fear strangers from a young age, especially strange males, and it’s possible that the scent of such individuals triggers a ‘fight or flight’ response — whose observed effect is an elevated level of cortisol.

“This could happen without us being fully aware of it,” she adds.

The findings are yet to be definitive, however. The sample size is relatively small, and this study only looked at the interaction between smell and cortisol in women — who were shown to better handle stress. So more research is needed to determine whether it holds true for larger swaths of the population, and in particular, if men experience similar effects.

Still, for now, the findings offer a quick pick-me-up when your boo is out of town. But they could point the way to new stress-management strategies. For example, the team suggests packing an item of clothing that was worn by a loved one when the job takes us far away from home, to help us relax.

The paper “Olfactory cues from romantic partners and strangers influence women’s responses to stress” has been published in the Journal of Personality and Social Psychology.

Drugs sign.

Chronic cannabis use seems to “blunt” our stress reactivity, paper reports

Chronic cannabis users may be more resilient to stressful situations, new research suggests.

Drugs sign.

Image via Pixabay.

The team, led by Washington State University clinical assistant professor of psychology Carrie Cuttler have compared cortisol (a stress-hormone) levels in chronic cannabis users and non-users during a stress-test. They report that the former show a much dampened physiological response to stress and stressful situations.

Stressing for science

“To the best of our knowledge, this is the first study to examine the effects of acute stress on salivary cortisol levels in chronic cannabis users compared to non-users,” Cuttler said.

“While we are not at a point where we are comfortable saying whether this muted stress response is a good thing or a bad thing, our work is an important first step in investigating potential therapeutic benefits of cannabis at a time when its use is spreading faster than ever before.”

The participants were asked to self-report their cannabis consumption habits, which the team used to split them into two groups: chronic cannabis users (40 participants), with daily or almost-daily use for the previous year, and non-users (42 participants) who had consumed the drug 10 or fewer times during their life and none at all during the past year. All users were required to abstain from use in the day the tests were performed.

All participants provided a saliva sample upon arrival at the lab, which the team used to determine their baseline stress levels. Then, members of both groups were randomly assigned to take the high-stress or no-stress version of the Maastricht Acute Stress Test, or MAST. This is a common tool for stress-related research and combines physical, psychosocial and unpredictable types of stress.

The no-stress variation required participants to hold their hand in lukewarm water for 45 to 90 seconds, and then count from 1 to 25. For the high-stress variation, participants held their hand in ice cold water for the same period of time then count back from 2043 by 17. They were given negative verbal feedback whenever they made a mistake, and were monitored by a web camera whose video feed was played back to them to up the stress factor.

Immediately after the test, all participants gave a new saliva sample to rate their current levels of stress. Before departing, the team also took urine samples to check on the participants’ self-reported cannabis use with their THC levels.

Mellow out

The researchers report there was no significant difference in the salivary cortisol levels for chronic users before or after the tests. For non-users, however, cortisol levels were much higher after the test than at baseline. The results add to a growing body of literature linking cannabis use to reduced adrenal and emotional reactivity.

Whether or not this is something you’d want, however, is still up for debate. On the one hand, Cuttler’s team says cannabis may have some use in propping up stress resilience, particularly for people who have a heightened response to stressful situations. But they also explain that cortisol has a very important role to play. Cortisol allows our bodies to mobilize energy stores in response to dangerous situations, and as such represents a key adaptive system in dealing with threats.

“Thus, an inability to mount a proper hormonal response to stress could also have detrimental effects that could potentially be harmful to the individual,” Cuttler said. “Research on cannabis is really just now ramping up because of legalization and our work going forward will play an important role in investigating both the short-term benefits and potential long-term consequences of chronic cannabis use.”

The paper “Blunted stress reactivity in chronic cannabis users” has been published in the journal Psychopharmacology.

Higher emotional intelligence can make you more vulnerable to stress — if you’re a dude

Emotional intelligence can be a double edged sword, a new study has found — while it can attune you to the feelings of those around you, helping you interact with them better, it can also make you more predisposed to risk, the team reports.

Image credits Ryan McGuire.

We all know that having good social wits — emotional intelligence — is a really big boost for all your social endeavors. But does it only bring advantages to the table, or are there drawbacks to be had as well? To find out, psychologists Myriam Bechtoldt and Vanessa Schneider of the Frankfurt School of Finance and Management in Germany assessed 166 male students’ levels of emotional intelligence by asking them a series of questions to assess. For example, the participants were asked to look at photographs of faces and then estimate what emotions they were conveying, and to what degrees.

The same students then had to hold a mock job interview in front of judges who displayed stern facial expressions. To asses their levels of stress, the team measured cortisol (stress hormone) concentrations in the participants’ saliva before and after the talk. Students who rated higher on the emotional intelligence scale in the photo trial showed greater levels of cortisol during the second experiment and took longer to drop down to baseline levels.

Just like too much of a good thing can turn toxic, the findings suggest that some people simply could be too emotionally intelligent for their own good. By tuning in to others’ emotions so accurately, they become highly sensitive to their effects, which can put them under a lot of stress. Some sensitive individuals may even assume responsibility for other people’s sadness or anger, which ultimately stresses them out, Bechtoldt adds.

The study remains limited in sample size, age distribution, and in only studying male participants — further research is needed to see if this relation between emotional intelligence and stress plays out differently in women, different age groups, or people with other educational backgrounds. But it does illustrate some pitfalls of highly emotionally intelligent people — and why learning to cope with emotions is a crucial skill for them.

The full paper “Predicting stress from the ability to eavesdrop on feelings: Emotional intelligence and testosterone jointly predict cortisol reactivity” has been published in the journal Emotion.