Dangers of Mastubation:

Masturbation to sleep is an unhealthy way, young teens or adults discover themselves or hear from friends to offset the imbalance from mental and emotional disturbance to go to sleep.

Masturbation with wet or dry ejaculation releases Dopamine (happy hormones), endorphins, etc and the human psyche goes momentarily to slightly higher dimensions and goes back to depressive and frustrated mode. They think they come back to the same earth dimension at the end of each masturbation, so what is the big deal?

No, the mastubator psyche slowly and steadily gets addicted to darker and darker depressed psyche levels and constantly lures one deeper and deeper into it. One can equate these to hell dimensions. The mastubator is lured into these hell dimensions by momentary pleasure. One day, he cries that he finds no happiness and is motivated to end his life or search for some other higher form of happiness elsewhere, it is because he habitually lured himself in that direction. 

Dry vs wet Ejaculation: Psychihc perspective 

Training the genital region muscles for dry ejaculation can get dangerous and eventually landslide to wet ejaculation and dangerous addictions. Muscle memory in those regions, memory in the head, and kundalini are forming dangerous loops now that can make the individual hard to break the loop later on in his life. 

There are several lights from the base chakra, Sex intercourse-genitals chakra, and Kundalini attracts the attention of atma and buddhi down by projecting light from the bottom to the head. I will write a post on that.

"Sex You" book has accurately depicted all these internal lights during sex with pictures. There is one piece of information that was not included in the pictures of that book but it is mentioned in the Invision series books, it is about the travel of buddhi down to the genitals.

Buddhi has to travel down to the genitals to meet the kundalini there to reach sexual climax and ejaculate. Buddhi is elevated and it is best if it stays in the head if possible one has to relocate the kundalini from the base chakra to the head or neck, not the other way.

Constantly taking Buddhi down is a dangerous road to disaster and it is motivated by Kundalini and ancestral force. Even playful masturbation or masturbation for sleep, this process of buddhi going down to the genitals will be the same all the time.

Several of these age-old or tribal practices are spread out all over the world due to a lack of spiritual wisdom or environmental/ cultural pressure at that time & region, people glorify and package them as a cultural treasure and hand them over to the next generation as a gift, it comes with both good and regressive ideas.

When one discovers psychically or from a trustworthy source, one should try to unlodge them from the psyche if they can.

Itching is not the same as Sex (both biologically & psychically):

When one masturbates or has intercourse, the buddhi and kundalini meet at the genitals for the climax. Even without climax, if one prolongs a sub-climax pleasure for a long time, the buddhi actively moves back and forth from head to throat or chest or navel region, and when it reaches the genital, it shoots out. 

Scratching during Itching is a soothing process, when one scratch Serotonin hormone (another happy hormone) is released in the body, and soothes the brain, and can even lead to sleep. One keeps scratching more and more as the brain likes serotonin and one stops until the skin protests saying "Idiot, a few more scratches, I will bleed and suffer! Stop it stupid brain from jugging serotonin".  Even now if someone scratches my head, I will fall asleep.

Why adults don't get attracted to scratching their heads for pleasure strongly?

Scratching the back, head, and legs is different from scratching the genital region.

Psychically, scratching at local regions releases cell kundalini, no buddhi travel takes place, just harmless pleasure and minor releases.

But scratching at the genitals area or any kind of prolonged touching is dangerous, it kicks and awakens the ancestors, kundalini sleeping at the base chakra is triggered and eventually, kundalini awakened like that will not go to sleep again until it has pulled buddhi down to genitals and have a union with him.

Are some variants of sexuality not about nutrition or nourishment need?

From the surface, everything looks like love, a compulsion or soothing for mento-emotional trauma but deep down, the idea of soothing and compulsion itself sets the stage for the need for eventual nourishment in some form.

When one is starving for food, the food touching the tongue itself is an act of soothing and nourishing the compulsive need of the body for gross food. 

Similarly, some need encouraging/appreciative or pleasant words from time to time for mental nourishment, some need sex in some form to manage the compulsive need for reproduction faculty, and this act of sex itself is nourishing for the other person.

Everything boils down to the exploitation of nature in the form of action and nourishment/ satisfaction from nature in form of returns.

Why jivatma always wants nourishment bliss all the time?

In the Uddhava Gita and Upanishads, there is this famous story of 2 birds:

Uddhava Gita: 2 birds sit in a tree, one bird eats the fruit and the other big bird is happy and had no craving to eat the fruit. One is the Jivatama and the other is Paramatma. 

**Adi Shakara restated this analogy from Upanishads as "Small bird touching the fruit is buddhi and the big bird not touching the fruit is Atma".

**This restatement of Adi Shankara will lead to an inference of jivatma being absolute like Paramatma but that is not the reality. But without extending the analogy beyond its precincts, this 2 bird analogy is enough to understand both the atma & buddhi behavior and jivatma and Paramatma distinction. 

Jivatma is eternally handicapped and compelled to crave and touch the fruit of exploiting nature whereas the Parmatama (the big bird) is existentially satisfied with its own nature and had no need to touch the fruit to find nourishment or satisfaction, it's existential location is way outside that of jivatama.

As long as atma is not happy by itself, "Atmena Atmam" (Self on Self) is mentioned in Gita quite often in various contexts, one would keep touching anything and everything. Atma touching the buddhi thru a sense of identity is the very first act of exploiting nature, the bird touching the fruit.

When one separates the atma from adjuncts (even for a brief time consistently), one will experientially know not just intellectually that everything happening around is a form of exploitation by atma and it gets nourishment bliss in return for its exploitation and this nourishment bliss motivates the atma to exploit more and more for this temporary bliss.

It is an endless loop unless one finds bliss in being "Self on Self" and that bliss is neutral and fulfilling, until then the journey of transmigration and all-around exploitation and nourishment continues!