I’ve found that this particular topic is a favorite amongst my patients and I’ve loved the creative ways they have utilized it. Quick note: if you don’t yet feel fluent with the Sympathetic Nervous System (SNS, commonly thought of as the “fight or flight” or stress response) and the Parasympathetic Nervous System (PNS, commonly known as our “rest and digest“ or relaxation response), you might back up and read the previous posts …

So, like all humans, you find yourself in a situation of suffering: you’re triggered, anxious or angry … it probably doesn’t come as a surprise that this is likely your SNS activating or some degree of ‘“fight or flight.“ What may be less obvious to you, is that your SNS activation is making your hands colder. I’ll get into why this knowledge is a bit of a superpower, but first the physiology …

Why does stress make our hands colder? The SNS innervates blood vessels and controls the constriction, or vasoconstriction, of our blood vessels. The PNS doesn’t innervate the blood vessels in our hand, it’s only the SNS.

So when the SNS revs up, our blood vessels vasoconstrict …

Constricted blood vessels = less blood flow

Less blood flow = less warm blood

Less warm blood = colder hands

Therefore, stress (SNS) leads to colder hands in most people.

The opposite is also true … when our hands get warmer (assuming the environmental temperature didn’t change), that means that our PNS is running the show.

So that means that, barring some outside change in temperature or other medical reason you may have for sudden hand temperature changes, when you feel your hands warming as you consciously allow your body to relax, your SNS is starting to quiet down.

That is incredibly helpful to data to have about your autonomic functioning in any given moment.

How is this fascinating nugget useful?

Awareness and insight: when your hands are cold or warm (and these changes happen because of stress / relaxation), this might be an indicator for you of your level of SNS activation. I have a few patients that use warm hands as a way to verify that they aren’t as deep into “fight or flight“ territory as it seems.
Changing your psychophysiology and emotional state: by engaging in some simple techniques, you can reduce your SNS activity and, over the period of 5-10 minutes, start to feel your hands warm up. Being able to consciously warm your hands (as sci-fi as that sounds, it’s very doable) is actually part of how biofeedback treats migraines and stress-related hypertension.
Learning to allow rather than control: one of my favorite things about learning to warm your hands consciously (i.e. activate your PNS or vagal brake to the point that SNS withdraws) is that that the harder you try the worse you do. In fact, I sometimes illustrate the futility of trying to control inner experiences by asking my patients to please, please try your very hardest to make that temperature go up. This makes their temperature go down because they are efforting; and efforting is an SNS function. So learning temperature biofeedback teaches us to allow and to notice rather than to try or to force.

I’m a ‘temperature stress-responder’ myself ~ my hands are often in the 70s (Fahrenheit) especially if I’m giving a presentation or really concentrating or just stressed. When I meditate, I get up into the 80s and probably 90s at times. For context, most men and women are in the high 80s Fahrenheit in a neutral situation. I remember one time I shook an Irish women’s hands; noticing my hand temperature and said: “You know what they say: cold hands, warm heart!“ Even if not physiologically true, I like believing it!

Anyway, if your hands are often cold like mine, you might also be a ‘stress-temperature responder‘ and could benefit from some of the techniques I teach my patients to feel confident that they are tamping down their SNS by warming their hands:

Breath-focused concentration meditation (probably the most common form of meditation practiced)
Mindfully putting your attention on any sensation in your hands (this may be a pulsation, or other form of energy; if you’re very interoceptively aware, you might be able to feel each pulse in different parts of your hand)
Imagining being in a favorite, warm place - warming your hands over a campfire with friends, being in the sun on a beach, holding a mug of your favorite warm drink
Hypnosis, autogenics, guided imagery or any other relaxation technique you’ve been trained in (I doubt progressive muscle relaxation would work)
Breathing at 6 breaths per minute using a breath pacer (there are apps and websites)
Generating positive emotional states such as gratitude, compassion, loving-kindness (here’s a Buddhist approach to this; though the field of positive psychology is replete with such strategies)

If you were in my office, I would put a sensitive thermometer on your finger to measure these changes and reinforce what is working; but you can do this on your own! It takes patience … I call temperature the “tortoise“ of psychophysiology, so it’s important you try one or more of these practices long enough until you can perceive warming; for some people this awareness happens after only a couple of degrees F increase and for others it takes 5-10 F increase. Another way to go is to purchase a cheap ‘stress thermometer‘ off Amazon; I’ve not used one myself so I can’t speak to it, though I’m confident it’s likely not as sensitive as what I use and more accurate than guessing. A third, highly creative method, popularized by the brilliant Erik Peper, PhD is to put a piece of milk chocolate between your fingers and relax until you get enough vasodilation to melt it (suggesting you are at or above 86-90 degrees F); when you get better, you can move on to dark chocolate! What’s interesting about using dark chocolate is that, apparently, the melting point is 90-93 degrees F which is almost at my training goal for most people of 95 degrees F. I would think that this method would hands-down win for most fun …

Whether you choose to get professional temperature biofeedback (which usually involves other forms of biofeedback) or any of the DIY methods above … the measurement is so much less important than getting in touch with your body in a way that helps you regulate your Autonomic Nervous System (ANS).

While this can be helpful for anyone, there are some people who’s hands are always hot so there’s not a lot of room to improve; finding and intervening on stress in other body systems would be the way to go for them (e.g. muscle tension, HRV, etc.). One other important note: you won’t find success warming your hands when you’re highly stressed; it’s best to start this training under normal circumstances and get good at it. Eventually you’ll be good enough to tamp down a larger SNS activation (using your vagal brake).

I hope this simple technique helps you have some awe about your body and feel more confident in reducing SNS activation in your body. Try it out and let me know what you learn!

References:

Freedman, R. R. (1991). Physiological mechanisms of temperature biofeedback. Biofeedback and Self-regulation, 16(2), 95-115.
Peper, E., Johnston, J., & Christie, A. (2009). Chocolate: Finger Licking Good An Economic and Tasty Temperature Feedback Device. Biofeedback, 37(4), 147-149.