Spanking, flagellation and cockbinding; researchers at the University of Northern Illinois have been very naughty in their attempt to quantify physiological responses to sadomasochistic activities.

 In their Archives of Sexual Behavior publication, the stress hormone cortisol along with the dominance associated testosterone hormone was measured in 58 sadomasochistic practicing couples before and after kinky sex fun time. 

Their results, along with a review of S&M literature suggests couples that practice S&M experience reduced levels of stress and feel an increase in relationship closeness.

In order to measure hormone levels, the Illinois researchers collected saliva samples from S&M party goers.  Although most of us are a bit shy in regards to sharing our personal sex life, the S&M community was apparently quite eager to help.  In fact, participants were so eager to take part, that the researchers ended up with an incomplete data set:
Unfortunately, most participants begun their scenes without providing pre-scene samples, and SM community norms prohibited us from interfering with scenes once they begun.  Thus, pre-scene samples were collected from relatively few participants.
In general, incomplete data sets for statistical analysis aren't good for discovering real correlations.  However in this instance, we must sympathize with the researchers since no information, even if it's for the greater good of scientific knowledge, is worth interrupting a leather daddy with a horse whip.

With such a dynamic group of subjects, obviously over-eagerness wasn't the only occurrence of breaching the S&M sampling protocol:
One of the 12 women who performed the bottom role had indicated on her pre-scene questionnaire that she would be performing the top role.  On her post-scene questionnaire, she explained that she had, "planned on topping&wrote that on [the] 1st form.  [But] ended up meeting two friends and bottoming to them."
This woman was later flogged as a punishment for being un-cooperative with researchers.  Arguably, laboratory mice would have been easier to control, but miniature gags and paddles are a tough find.

Speaking of the quest for greater and necessary knowledge, just collecting saliva samples before and after each S&M scene wasn't enough for these deviant scientists; in order to gather psychological data, researchers observed the actual S&M scenes themselves and even took notes:

11:00 pm: Hand restraints placed
11:02pm: Bottom disrobes, faces north
11:05pm: Bottom Kneels


You get the idea.

Just in case you're questioning the validity of the study and therefore the qualifications of the researchers themselves, rest assured, at least one researcher who took notes during the S&M scenes has stellar qualifications:
The observer was familiar with academic taxonomies of SM behaviors and SM-community taxonomies and had observed SM scenes on other occasions prior to data collection.
Now that we've determined that experts were present during sample collection, the only other question left to be asked is what exactly is the purpose of this study anyway?
The goals of the present studies were to examine the physiological and psychological effects of consensual SM activities and to document SM behaviors that fall outside of the current taxonomies in the academic literature.
Surely with this level of relevance, the usage of force wasn't necessary in order to obtain grant money to fund this project.

As for the physiological results of this study, researchers predicted that cortisol levels in individuals playing the bottom role (one that follows orders, receives stimulation, is bound, etc...) would have an increase in cortisol levels followed by a drop in cortisol after the scene was over.  In other words, people that are knowingly about to place themselves in a situation that includes physical pain and other stressful activities, such as sensory deprivation, were predicted to have an increase in stress hormones and once the activity ends, are likely to have a decrease in stress hormones.  To sum up this highly climatic portion of the study, their hypothesis did indeed turn out to be true.

In regards to testosterone which is often an indicator of status in dominance hierarchies, it was hypothesized that perhaps individuals that assume top roles (gives orders, provides stimulation, etc...) would have a higher baseline testosterone level.  This however was not the case, bottoms had higher levels of testosterone (both males and females) than tops.  The authors suggest that one explanation for this occurrence is that testosterone levels could have been increased due to the anticipation of an endurance-like challenge.  This explanation for heightened testosterone in bottoms makes sense considering in S&M, you've got to be prepared to take it like man.

Relationship closeness was also assessed immediately after the S&M scene took place.  Subjects who reported that their scene went well, indicated that they felt closer to their partner afterward.  This isn't surprising because even though S&M often includes hot wax, skin branding and enemas, intimacy is actually a big part of S&M; tops really do care about their bottoms as illustrated in this touching observation of human kindness:
...the top noticed that the bottom, who was bent over a table, was moving one foot around, unable to rest it evenly on the floor.  The top paused the scene activities and placed a pillow under the bottom's foot to relieve the discomfort.
If placing a pillow under your slave's restless foot during rimming isn't a true sign of affection, then I don't know what is and I'll remain gagged on the subject.

Although the researchers of the study surprisingly state that, "...sadomasochism has received limited attention from researchers," there is however, enough literature published to cause major controversies within the field.  For example, Alison et al. (2001) empirically derived that flagellation should be categorized under humiliation.  However, this new research contradicts that claim:
Participants also engaged in flagellation using floggers and whips, although it appears from observation and casual conversation that the tops used flagellation as a method of administering pain rather than as a way to inflict humiliation...
Traditionally, sadomasochistic sexual practices are considered to be a psychosexual disorder.  However nowadays, only closed-minded prudes think that.  Although caning, nipple clamps and nut stomping might be a bit out of your personal comfort zone, surveys suggest that a "substantial minority of people engage in or fantasize about such practices today."  In fact, people have been incorporating pain and bondage into sexual practices for thousands of years.  Chances are if you haven't fantasized about it, your partner has.

So the next time you and the Misses are feeling a lack of intimacy bust out the rabbit fur blanket, agree on some safe words, lower that sex swing, and let the spankings begin!

Further Study: Walk All Over Mebecause it has Tricia Helfer as a dominatrix and Battlestar Galactica is over.

Walk All Over Me Leelee Sobieski Tricia Helfer

References:


Alison, L., Santtila, P., Sandnabba, N. K., Nordling, N. (2001).  Sadomasochistically oriented behavior: Diversity in practice and meaning.  Archives of sexual behavior 30(1):1-12.

Sagarin, B. J., Cutler, B., Cutler, N., Lawler-Sagarin, K. A., Matuszewich, L. (2009).  Hormonal changes and couple bonding in consensual sadomasochistic activity.  Archives of sexual behavior 38:186-200.