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All about endorphins in kink – Interview with Hermes Solenzol

When I am asked why submitting to pain is fun, I usually provide a quick-and-dirty simplification of the so-called “endorphin ecstasy”, or “subspace”. It goes like this: sexual arousal increases the thresholds for pain and stress. When your organism experiences enough stress, it releases opioid-like molecules that give you a powerful high. So, in certain conditions, some people happen to enjoy a painful stimulation… and it can become very pleasurable.
This also is the often-repeated explanation in kinky books and seminars – yet it is far from being comprehensive, not to mention entirely correct. Luckily, I have stumbled on a very interesting article on the subject by the best possible source ever: a specialized neuroscientist and kinkster. So how could I help picking his brain about it?


First things first, can you please introduce yourself to my readers?

Hermes Solenzol

Hermes Solenzol

I would define myself as a kinky neuroscientist and an intellectual with a wide range of interests. I am a cosmopolitan, born in Rome from Spanish parents. I grew up in Spain under the care of Opus Dei, a conservative catholic organization. At 15, I had a religious crisis that made me leave Catholicism and start a spiritual search. During my compulsory military service I narrowly escaped having to rebel to the 1981 military coup. After finishing college, I moved first to Paris, and then to the United States to do a postdoc at the National Institutes of Health. I had long been interested in sadomasochism, and in Washington DC I found a BDSM organization called People Exchanging Power then, and now the Black Rose. There I met the woman who is now my wife. We have been living in California for over 30 years, where I have been a member of Threshold, the local BDSM organization, since we arrived.
For the scientifically inclined, here are links to my bio and to a list of my scientific papers.


Your unique history puts you in a great position to examine the in-and-outs of some aspects of kink that are often talked about but only in anecdotal terms. One example would be endorphins, which happen to be a rather more complicated subject than the usual «and then endorphins kick in» throwaway phrase that most BDSM enthusiasts know. As a matter of fact, how much does science actually know about these molecules?

Science knows a lot about endorphins and their receptors because research on addiction to opioids has been generously funded by the National Institute of Drug Abuse in the USA.
Endorphin is a portmanteau for a group of almost 40 peptides that are more properly called endogenous opioids. They belong to four families – enkephalins, dynorphins, endorphins and nociceptin/orphanin – which are encoded by four different genes and processed by four different receptors in various combinations.
A large part of my research was devoted to study the release of endorphins in the spinal cord of rats – I found a new way to measure it. Another Spanish neuroscientist, Jon Kar Zubieta, found a sophisticated way to measure endorphin release in awake humans. He injects them with an opioid that contains isotopes that can be detected by Positron Emission Tomography when they bind to the opioid receptors. This allows to see how endorphins do different things in different brain areas. There is no “endorphin soup” all over the brain, but a very localized release.
Endorphins are also released into blood, but they do not cross the blood-brain barrier that separates the blood from the brain. Hence, measures of endorphins in the blood – which have been touted to detect the endorphin high – cannot really tell you what is happening in the brain.


I found you through your articles about the science of subspace in particular—and even as a longtime enthusiast, I was struck by your pointing out that there is no one ‘subspace’ but three. Can you elaborate?

I wanted to study the neuronal pathways that connect the brain with the spinal cord and drive endorphin release when we are in pain. They originate in an area of the brain stem called the nucleus raphe magnus (NRM). However, there is another neuronal pathway from the brain stem to the spinal cord that also inhibits pain, but uses noradrenaline as the neurotransmitter instead of endorphins. This pathway originates in three brain regions called the nucleus coeruleus, A5 and A7. The odd thing is that I found that noradrenaline inhibits the release of endorphins in the spinal cord. Digging in the literature, I found that there are mutual inhibitory connections between the NRM and the three noradrenergic nuclei of the brain stem. That indicates that there are two mutually exclusive analgesic states, one driven by endorphins and one driven by noradrenaline. They are connected to different mental states. Noradrenaline release happens during fight/flight situations, which are accompanied by activity and alertness. Endorphin release happens during freezing behavior and other conditions where we become immobile and lethargic.
I thought that this may be connected to subspace in BDSM and wrote about it in Fetlife. A woman with the nickname of Glass Hummingbird wrote back to tell me that she could induce these two different subspaces at will, and had a way to detect them. She was a nurse, so she measured heart rate with a pulse oximeter. Endorphin release lowers the heart rate, while adrenaline increases it.
I was skeptical. She offered to come to Los Angeles and show me. So we got into a motel room with our BDSM gear and a pulse oximeter, and started playing. When I caned her or paddled her, her heart rate would go up and then down, so she got a noradrenergic subspace followed by an endorphin subspace. As she said, she could induce both at will, without any pain stimulation. Indeed, she showed how she could increase her heart rate to more than 110 beats per minute.
Then it was my turn. She didn’t know how to do impact play, so she stuck needles on me while I had the pulse oximeter on my finger. She played music while we did that. The needles hurt at first, but then I got into a deep subspace in which the music became extremely beautiful, just like when you take cannabis. She told me that my readings of the pulse oximeter went all over the place, sometimes up, sometimes down, so we couldn’t tell if I was in a noradrenergic or endorphin subspace. I may have fluctuated between them.
More reading and thinking lent me to hypothesize that there could be a third subspace characterized by the release of serotonin, but I haven’t been able to explore that experimentally, like with the other two subspaces.


Thank you for the clarification, and for sharing this amazing story. I guess the obvious next question would be asking whether there is any suggested way to elicit each kind of subspace reaction in particular.

Other people I met in Fetlife are doing their own experiments with pulse oximeters. It seems that when you start a scene, the first things that kicks in is the noradrenergic state. In the right conditions, the endorphin subspace kicks in after a few minutes, and it can last for hours.
I think that keeping the bottom engaged leads to a noradrenergic subspace, which can be fun and healthy. Screaming, struggling, stomping, talking back… these are things that are typical of fight/flight responses and therefore maintain the noradrenergic subspace.
To facilitate the endorphin subspace, the first thing we need to do is to create an environment of trust that allows the bottom to let go. A bit of sensory deprivation can help, like a blindfold. That way, the bottom can focus on the pain and other sensations. Laying down or having supportive bondage (for example, tied to a Saint Andrew’s cross) that allows for muscular relaxation also helps. The top should speak clearly and slowly, using a low voice, which can have a hypnotic effect. The bottom should be allowed to make noise, but avoid talking. The idea is to be drawn to the sensations of the body, not to the outside environment.

Una complessa molecola di beta-endorfina

A complex beta-endorphin molecule

You also wrote about how understanding the neurochemistry of subspace allows to better understand the sub-drop phenomenon, where some people experience delayed distress after an otherwise pleasant kinky experience. Can you tell me more about it—and maybe how to prevent or treat it as well?

Based on what I have heard, and a bit on personal experience, I think that there are two types of sub-drop.
The first happens immediately after a scene. It seems to be a natural consequence of the high achieved during that scene – what goes up has to come down. After a period of stress, such as the pain and anxiety during a scene, the body activates the parasympathetic system. This is a branch of the autonomous nervous system that brings the body back to balance. The heartrate slows down. The blood withdraws from the periphery and goes into the internal organs, which makes us feel cold, particularly in the hands and feet. We may feel thirsty or hungry. Emotionally, there may be a need for connection, physical contact and emotional support. However, some introverts who do not have a strong connection with the top may prefer not to be touched and be left alone with their thoughts.
Therefore, to deal with this first type of sub-drop, the top needs to provide aftercare. For most people, this includes getting wrapped up in a blanket, being held and being told encouraging things. Maybe some small talk. Water and a little food can help. Processing the scene should be saved for later, unless the bottom feels the need to discuss it immediately. Other people may not want to be touched or talked to, but observed at a distance.
The second type of sub-drop happens one or two days after the scene. Hence, it is much more difficult to deal with. It’s a feeling of low energy and unexplained sadness, sometimes bordering on depression. I think that it may be some kind of withdrawal from the endorphins and other neurotransmitters released in the brain during a scene. There is not much that one can do about it. Being able to recognize it and label it helps, because we know that it would be gone in a day or two. We should avoid stress and focus on activities that replenish our energy. This changes from person to person – for me, it’s reading. For others, it could be a walk in nature, watching movies, yoga or meditation.


Thank you for taking the time to share your insights. Before closing, can you point us to more of your works online?

I will publish my novel Games of Love and Kink this summer. It’s a romantic story about a young couple discovering BDSM. The story is set in Spain in the late 70s, a time in which Spain was going through a huge social change, transitioning from dictatorship to democracy. My characters also experiment with open relationships and do kinky games with other people. This is the English version of the first of my five novels in Spanish. More information about it can be found here.
My website Sex, Science & Spirit has a blog with lots of articles, not just about BDSM, but about sex, science, philosophy, politics and other things. I also write a lot in Medium and in Fetlife.

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