When I began my doctoral program in clinical psychology, I was prepared to grapple with complex theories and to be tasked with mastering some jiu jitsu-like therapeutic techniques in order to successfully work with patients. I was not expecting to find myself, as I did one day early in my training, with my face submerged in freezing cold water while hooked up to a heart rate monitor.
Why was I hooked up to a heart rate monitor with my face under water? Because it turns out that age old wisdom holds up. And modern science can help us understand why, but it doesn't change the fact that dunking your face in freezing cold water is actually one of the most effective ways to naturally regulate your nervous system.
In fact, splashing cold water on your face, timeouts, and deep breathing all work because they all basically do the same thing - they decrease your body's "fight-or-flight" response. They obviously look like very different behaviors, but modern science confirms that these techniques all have a similar effect on the body when done correctly and consistently.
And in order to do them correctly and consistently, we must first understand how it is that they decrease arousal. And that's where the science comes in.
Splashing cold water on your face:
When your face comes into contact with cold water, it triggers what's known as "the mammalian diving reflex." The hallmark of the mammalian diving reflex is a significant reduction in heart rate (it will slow down by 10-25%). Think about it, if your face is under cold water, there's a good chance that your body needs to conserve energy and oxygen immediately, so that's what it attempts to do by dropping your heart rate. Because the sympathetic nervous system operates as somewhat of a feedback loop, decreasing activity in one organ or system (the heart) signals to other organs (lungs, gut, etc.) that they too can transition out of a high state of arousal (fight/flight).
So, in order for splashing cold water on your face to work, it has to trigger this mammalian diving reflex. This means the water must actually be cold (if you're not sure if your tap water is cold enough, fill a sink or bucket with water and add some ice cubes to it). For optimal results, try actually dunking your head in the water or holding it underwater for a few seconds. For an adorable example of what the mammalian diving reflex looks like in action, check out this link.
Taking a time out:
When we are upset or anxious, it often seems like we need to resolve the problem at hand in order to feel better. In reality, we will usually feel better if we effectively turn our attention away from what's provoking us, rather than focusing on it. Again, the science here is pretty straightforward: Your body simply cannot sustain a state of alarm or intense activation forever. Once the trigger for your reaction is removed (taking the timeout), your body will naturally seek homeostasis and will thus slowly return to baseline.
Given the science, we know that in order for a timeout to work, it actually needs to be time away from what's upsetting us. This is often difficult because, let's face it, even if we leave the room, our thoughts usually follow us. When timeouts fail it's usually because we've failed to effectively turn our attention away from the problem; we end up just ruminating about it in another room while doing something else.
An effective timeout is thus one in which you physically leave the situation that's provoking you, and mentally turn your attention towards something else rather than reflecting on the problem. There's all sorts of tricks for doing this. You can try coming up with words that start with the same letter, or count forward by 3 for 5 minutes. I personally rely heavily on my chess and NY Times crossword apps. They require my full attention, but don't get my heart racing.
One last note about effective timeouts, they need to be time limited. A timeout implies that you will return to the situation once you've calmed down a bit. If you don't return to the situation you are basically just practicing avoidance, and while that may help in the short-term, it's likely to wreak havoc on your life in the long-run.
This technique is similar to splashing water on your face: When we regulate one component of the sympathetic nervous system - in this case, our breathing - we end up decreasing arousal across the entire system.
When our fight-or-flight response is activated, our breathing becomes shallow and rapid, resulting in an immediate increase in oxygen in the bloodstream and muscles. This facilitates short bursts of energy like that which is required to fight or flee a predator (it can also cause hyperventilation and the subjective experience of anxiety).
Conversely, when we are in a state of relaxation our breathing is slower and deeper. The scientific term for this deep breathing is "eupnea", and it's observed in all mammals when they are resting and there is no clear or present danger in their environment.
In my experience, the easiest way to transition into deep breathing is to place one hand on your chest and one on your stomach. As you inhale allow your stomach to fill slightly with air while keeping your chest still. As you exhale, allow your belly to collapse, again while your chest remains still. If done correctly, you will likely resemble a sleeping baby whose tummy swells and collapses with air, with very little observable movement in the chest.
So there you have it: three age-old pieces of advice that actually check out. That's not to say everything your mom told you to do when you were upset will help, but who knows, science might just continue to prove her right.