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This image is often shared on social media with captions like “These are the consequences of sleeping with a fan on” or “Sleeping under an air conditioner caused this.”
However, there is no credible medical evidence that sleeping with a fan or air conditioner causes veins or blood vessels to appear like this. Health experts have repeatedly debunked these viral claims as misleading.
The image itself shows a network of dark, branching blood vessels on the side of a person’s neck. Without the original source or medical history, it’s impossible to determine the exact cause. Possible explanations include: