An American mattress company has sought to reassure customers that it is not hiding microphones in their beds, after alarmed snoozers noticed references to audio recording in the company’s privacy policy.

Under a heading explaining which personal information Sleep Number collects, the company, which makes smart mattresses with adjustable firmness, said it “may” collect “audio in your room to detect snoring and similar sleep conditions” as well as sleep-related data such as “movement, positions, respiration, and heart rate while sleeping”.

Concerned owners began contacting the company after Michael Farrell, a web designer who spotted the clause, shared it on Twitter. Farrell took the phrase to mean there was a microphone inside the mattress listening to users, prompting several to get in touch with the company asking how they could stop their beds from recording them while they sleep.

Sleep Number eventually responded to the questions with a statement saying: “Sleep Number’s beds do not record audio. We’re updating our privacy policy to clarify this.”

Some users, Farrell included, later speculated that the company may record audio through its companion app, which Sleep Number also denied in a following statement: “On the x12 model, the bed responds to preset voice commands that operate the bed and are not recorded. No Sleep Number products, including the app, record audio.”

When approached by The Guardian about why it wrote about audio in its privacy policy if it is not, in fact, recording any audio, a company spokesperson said: “Sleep Number’s products do not record audio. It was included in our privacy policy as we were developing a prototype with an auto-snore feature. That product was never launched and we’re working to clarify this in our policy statement.”

The rise of smart devices, which can connect to the internet or to other electronics to provide extra features, has led to concerns from privacy campaigners that users are voluntarily introducing surveillance into their lives.

In a report in June, the consumer organisation Which? detailed the “staggering” level of corporate surveillance British homes were vulnerable to.

The investigation found televisions selling viewing data to advertisers, toothbrushes with access to smartphone microphones, and security cameras that could be hacked to watch and listen to people in their homes.