Two different things often get bundled under this question, and separating them is the first honest step. One is electromagnetic sensitivity, the belief that fields from phones, routers, and power lines cause physical symptoms. The other is technology-related stress, the ordinary strain of long screen time, constant notifications, and a mind that never fully switches off. Reiki is sometimes offered for both, but the two deserve very different answers.
On electromagnetic sensitivity, the science is clear and worth stating directly. People who report these symptoms are genuinely unwell and their distress is real, but careful blind studies have not found that they can detect electromagnetic fields, and there is no established link between everyday exposure and the symptoms reported. The World Health Organization treats the symptoms as real while noting there is no scientific basis for tying them to electromagnetic fields. Against that backdrop, the idea that Reiki shields a person, clears electromagnetic interference, or rebalances energy disrupted by devices has no support. There is no evidence for the energy field Reiki assumes, let alone for it counteracting another field.
Technology-related stress is a more grounded place for a relaxation practice. Hours of screens, fragmented attention, and the pull to stay reachable do leave people wound up, and a quiet session offers a clear contrast. An hour with no device, slow breathing, and unhurried attention can lower that tension, much as any restful pause would. The benefit comes from stepping away and settling the nervous system, not from anything Reiki does to electromagnetic fields.
The distinction matters for safety. Someone with troubling symptoms they attribute to devices deserves a proper medical evaluation, because the symptoms are real even when the suspected cause does not hold up, and other treatable conditions can be missed if everything is blamed on technology. A relaxation session is not a substitute for that assessment.
So Reiki has nothing to offer against electromagnetic fields, which are not the culprit the framing assumes. For plain technology fatigue it can serve as one restful break among many, a screen-free hour that some people find calming. The simpler interventions, time offline and better sleep, do most of the same work.