i wanted to lucid dream but i'm too scared to try, here's why

so it all started when i was talking with a friend and he told me about lucid dreaming, i looked it up on youtube and after watching a few videos about lucid dreaming i came across this one video where some person said that you can heal yourself in lucid dreams by making your brain believe that you're healing something (whether it's a physical body part or something mental or psychological), and the more you believe, the more your brain heals you, in other words it's just a placebo effect. when i finished watching the video, i thought to myself: if you can heal yourself in a lucid dream, does that also mean you can harm yourself by tricking your brain into believing that you have some sort of disease, for example, a brain tumor. now i just can't sleep because i'm having intrusive thoughts about all of this and i'm that i might trick my brain into believing that i have some sort of disease in a lucid dream.

Lucid dreaming is one of the safest natural forms of personal mind exploration available. Like with everything, I would consider the source of that information because there is no research that you can heal yourself in lucid dreams by making your brain believe that you're healing or harming anyone.
A lucid dream is technically nothing more than a normal night's dream with self-reflective logical consciousness added into the mix. In theory, this should be entirely safe.
That said, lucid dreaming is an exotic state of mind, poorly researched, and the evidence is not clear on if regular lucid dreaming is beneficial, neutral, or even damaging.
What is known is that regular disruption of one's sleep cycle is known to have negative health impacts, so this is best avoided. Excessive regular lucidity could, in theory, have a similar detrimental impact. However, this remains unknown.
As with any dream, there is always the chance for scary, strange, or unnerving experiences. However, the knowledge that you are dreaming helps to keep these experiences fun, as you're fully aware that you're entirely safe in the virtual world of dreams—this knowledge is lacking in non-lucid dreams.

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Please don't afraid of that.
actualy, You are unable to harm or heal yourself (or somebody) unless You got a full and strong control of Your mind and will. But when You will get this kind of control - You will manipulae Your power with Yur mind and will harm Yourself only if You want it.

Also - not about lucid dreaming, but about Controlled Dreams - there was one person from russian DreamHakers, called Doc. Because he was able to heal people from Dreams. He goes to controlled Dream, find there a person who need to heal, and do his job.
There is a theory about this fenomenon. In our Dreams we can meet that locations as Labirynth - archetypical structure. some of tese structure can "catch" us and we will spend a lot of time trying to find exit - a lot of days and nights. We can remember our dreams as repeated or looped action, the same dream each night... In real world we became ill when this happened. so, Doc goes to Labirynth, finds the person and guide it to exit.