Wearable sleep trackers are using brainwaves to train AI without explicit consent

What happened

An investigation by Science, conducted with the Pulitzer Center's AI Accountability Network, found that wearable sleep and meditation headbands are turning the brainwave (EEG) data they collect into training material for AI models. The companies involved have accumulated tens of millions of hours of EEG recordings in total.

Which companies

Canada-based Interaxon, the firm behind the Muse sleep and meditation headband, has confirmed it trained an AI model on about 50,000 hours of EEG recordings and says it strips identifying information such as names, emails and addresses. Before speaking with Science, however, its privacy policy did not explicitly state that brain recordings could be used to train foundation models. The company has since updated the policy.

Emotiv, another EEG maker, is training its "Large Brain" model partly on customer recordings. It too updated its privacy policy after Science's questions, disclosing the use of de-identified neural data for model training.

Why it matters

According to the investigation, more than two-thirds of the companies studied explicitly allow corporate transfers of data without user consent. If a small neurotechnology firm is acquired, those recordings could end up with a new owner. Colorado and California have amended their consumer privacy laws to cover neural data, while other states lag behind.

Limits and risks

Experts stress that consumer headbands cannot read thoughts: they typically use one to six electrodes, compared with 19 to 25 in clinical EEG systems. Still, the privacy risk is real. In February, an engineer discovered he could access other people's brainwave recordings through a smart sleep mask he had purchased.