[mods this is the right one sorry]
EDIT: I'm really sorry if this is wordy. My dominant hand is immobilized so I have to use voice to text lol.
It is normal to feel exhausted after EMDR. It can certainly be fatiguing and take a toll. Flashbacks as visceral is the ones you are describing though, please make sure you're talking to your therapist about! At the bare minimum, the amount of processing (regardless of the modality used) should never exceed side effects that you can, reasonably, safely tolerate.
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(Too much, too intensely, too fast, is when we say we are "flooding." Flooding is, at best, short-term harmful/unproductive and, at worst long-term retraumatizing. The original goal of designing EMDR (outside of it being more refined and highly targeted) is it is supposed to be slower or gentler or more controlled than other forms of processing. Especially because at the time of its inception, the only type of processing out there was pretty much just full trauma disclosure, which is obviously too much. But EMDR is still a huge amount of processing and also can cross a fine line of being too much. I I know many of us already know this stuff but just to clarify what I'm referring to when I say processing)
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If any of my therapy programs were resulting in major flashbacks like I think you are describing, myself and my therapist would definitely know that we need to ratchet it down and move more slowly. Trauma treatment moves at its own speed.
It's more commonly understood now than ever before that EMDR has a very fine line between healthy processing and too much processing. (This is true for all types of processing.) For example some people with CPTSD will never be able to do EMDR, especially those with DID. It has the potential to be re-traumatizing or make things worse In this case. I've had cases where a session is limited to a maximum of 10 minutes talking about a certain trauma, and that's the highest level of processing that is safe and the rest of the session is spent stabilizing. (Maybe reserving time in your session to plan for coping, mindfulness skills, and self-care would be helpful? If you are not doing that already of course)
In any case I can't tell you what your treatment should look like that's between you and your therapist so I'm just kind of giving you a pile of information to decide what to do with how you see fit. That being said, it definitely troubles me that you are experiencing such high levels of distress after your sessions. Treatments like EMDR need to feel safe to work, and I'm not sure if that feels very safe to me! It leaves me worrying about you experiencing such awful flashbacks!