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Why Having To Pee While Driving Is As Bad As Drinking

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As a lifelong urinator, I like to keep up with all the latest innovations in the field. That's why I was excited to see one of 2011's Ig Nobel awards went to Dr. Peter Snyder, VP of Research at Rhode Island Hospital, and author of an important study called "The Effect of Acute Increase in Urge to Void on Cognitive Function in Healthy Adults."

Why so important? Well, I know from personal experience I've made some of my absolute worst driving decisions when I've really, really had to pee (crossing four lanes at once, ditching in a median, openly sobbing) so I was very curious to understand the science behind it all. Energized with a thirst for knowledge and a recently voided bladder, I gave Dr.Snyder a call to ask him if others had similar problems when feeling the urge to "go" while going. It turns out having to pee while driving is just as bad as drinking. Science!


Jalopnik: Hello Dr.Snyder. Before we get to how having to urinate affects the ability to drive specifically, maybe you could tell me a bit about how this line of research got started.

Dr.Snyder: Sure. We actually didn't set out to look at the question of the effect of witholding the urge to urinate on driving per se, but in the end it was obvious there were some very real-world ramifications for what we were looking at. At first, we used the urge to urinate as a model for a sort of temporary pain we could induce safely so we could test the reliability of some new cognitive tests we were developing.


The use of pain models to look at the effects on judgement and reasoning dates back 100 years; but ofte the pain models used are fairly noxious, like using electric shock or capsaicin, which is the chemical in hot peppers. We decided that using the urge to urinate, a pain we all know well, was safe, reversible, we can turn it off really easy, and it's cheap! The entire study cost us a couple of bucks! It's a pain model that's safe and doesn't have much ethical baggage associated with it.

Jalopnik: So you were looking for a cheap, easy way to hurt people?

Dr. Snyder: Uh, yes? We used this model to look at the reliability of some special instruments we were developing to see how responsive and stable they are when you look at change over time. When we look at cognition in people, there's a problem with practice effects— people just tend to get better by doing things over and over— so we were working on instruments that don't have that problem. We validated the instruments in lots of ways— sedatives, sleep depravation, alcohol, stimulants. Turns out they are stable, and since we used so many methods we can benchmark, put head-to-head different factors on cognition. If there's a degree of impairment in one technique, we can compare it to others.

In the case of the urge to urinate, we found when people are at their top threshold of pain, when they can't stand it anymore, the level of impairment on reason and problem solving is equivalent to about a 0.05 blood alcohol level. We know that because we've done the studies and can compare levels of impairment across multiple models. In the US, the legal limit is 0.08, but in Australia, where we've been doing a lot of this work, the limit is 0.05 (The 0.05 level is about two drinks for a 160 lb man, and within the limits considered to impair driving).

This has real world implications, because we know there's many professions where people are in situations where they can't get away to relieve themselves, such as long-distance trucking. There's all sorts of situations where people can't get away, and the point we made is that there actually are some consequences. The pain can be so intense that you're distracted, and secondly, there may be a neurologic basis. The areas of the brain used when you withhold urine intentionally, to keep muscles contracted, those areas of the brain are very close to the areas used for online reason and problem solving, working memory, so there may be some interference and an actual physiological basis.


Jalopnik: Wow. Is there anything special about the need to urinate as opposed to other sorts of pain? I know that when I've been driving and needing to really pee, I have a harder time concentrating than when I've driven with other types of pain, say a sore back or a blow dart in my neck or something?


Dr.Snyder: I don't know if it's related to a type of pain, but there's another factor with having to urinate, and that's that you have to physically and consciously hold it! With, say, back pain, the best you can do is get comfortable and try not to move. With urination, it's a very active process, as you know. It takes lots of concentration.

Jalopnik: Oh yeah. So unlike other types of pain, you can't distract yourself away from thinking about it.


Dr.Snyder: That's exactly right.

Jalopnik: So it's not just a pain situation, it's a focus situation.

Dr.Snyder: Right. And that was factored into the models.

Jalopnik: Did you do any tests specifically with driving and the urge to urinate?


Dr.Snyder: No, but that would be a phenomenal follow-up test. While that wasn't one of our initial focuses, it's an obvious real-world implication for what we've done.

Jalopnik: I personally feel like when I've driven with a 0.05 blood alcohol level, which, let's be honest, I probably have, I feel like I've performed better than when I've really had to take a leak. Am I imagining that? What's different?


Dr. Snyder: That's a great question. To benchmark the study with alcohol, we got undergraduates drunk. We enrolled for this study in about six minutes. As you can imagine, it wasn't hard to find volunteers. We looked at all sorts of measures, and one of the things we found was very interesting. When we brought people up, to, say, a 0.09 blood alcohol level— we got them very drunk. And then we watched them as they sobered up, and we found that people's perception is reasonably accurate as they're getting drunk but terrible as they recover. As they get drunk, their perception matches their performance. But as they recover, people uniformly believe they're recovering faster than they actually are. So you probably just thought you were less drunk than you actually were. We misperceive it.

Jalopnik: So, if you're driving, and you really have to pee, and you can't immediately pull over, is there anything short of wetting the seat that you can do to help?


Dr. Snyder: Um, no. There's not really anything you can do short of making sure it doesn't get to that desperate point in the first place. If you're on the highway at 70 mph, and you really have to go, you really are impaired. You can't let it get to that point.

Jalopnik: So you'd recommend just wetting yourself at that point?

Dr.Snyder: (laughs) If it were me, I'd say I'd just look for the widest point on the side of the road I could get over to without getting hit.


Jalopnik: Would you be an advocate of an in-car urination system of some type? Should it be mandatory or an option? And, if it was an option, would you get one on a new car you'd purchase?

Dr.Snyder: If my kids were still a little younger, I'd seriously consider it. I think for myself, I'd rather pull over. But with kids, it would beat having to stop every half hour.


Jalopnik: So you don't keep an emergency urine bottle in the car?

Dr. Snyder: No, but since I published this study, and after I won the Ig Nobel award, I can't believe how many people told me they do just that. I did a radio interview in Seattle, and several truck drivers called in and told me how much they study resonated with them and that they keep bottles in the car for just that purpose.


Jalopnik: Any plans to continue the research and do a more driving focused study?

Dr.Snyder: You know, that is interesting, and I very well may have a student for whom I'd suggest this as a focus.


Thanks very much to Dr. Snyder, and everyone, please, go before you leave.