Is my idea a medical device?
In one sentence
If your product, including software, is meant to diagnose, prevent, monitor or treat a disease, it is probably a medical device under EU law, and that changes how you build and sell it.
In the EU, medical devices follow the Medical Device Regulation, called the MDR. What decides whether something is a medical device is its intended purpose: what you say it is for, in your marketing, website and instructions.
A sleep tracker that shows how you slept is usually not a medical device. The same tracker claiming to detect sleep apnoea probably is. Same technology, different claim.
Medical devices are sorted into risk classes: I, IIa, IIb and III. Many software products that support diagnosis or treatment decisions end up in class IIa or higher. From class IIa upwards, an independent notified body must check the product before it can carry CE marking and be sold.
This takes time and money: a quality system, usually based on ISO 13485, technical documentation and clinical evidence. Many teams plan for more than a year.
Some startups deliberately design their first product without medical claims. It might support care without diagnosing, while they build evidence for a certified version later. That can be a smart strategy, but your claims must stay honest and consistent.
In Finland, Fimea is the authority for medical devices.