A Florida man has filed a lawsuit (PDF) against Fitbit, saying the company's claims that its devices can track sleep are false.

The plaintiff, James Brickman bought a Fitbit Flex in 2013. His case is seeking class-action status, hoping to represent consumers who bought any of Fitbit's line of products that include sleep-tracking technology. Those models include the Fitbit Force, Flex, One, and Ultra and 2nd-generation devices like the Charge and Surge.

The suit says that Fitbit devices "consistently overestimated sleep by 67 minutes per night," as compared to polysomnography, the most accurate type of tracking used by sleep scientists. Compared to actigraphy, a less-accurate measure, the Fitbit still overestimates by 43 minutes per night.

The lawsuit cites a 24-person study conducted in 2012 and published in the journal Sleep Health as the source of the statistics.

"The Fitbit sleep-tracking function simply does not and cannot inform the user how well they slept with any accuracy whatsoever," the complaint states.

Fitbit misleads consumers by presenting sleep data as "exact times and percentages," and at the "absolute very least," Fitbit failed to disclose important facts from consumers, the complaint states.

"Thinking you are sleeping up to 67 minutes more than you actually are can obviously cause health consequences, especially over the long term," the lawsuit states.

The lawsuit, filed in San Francisco federal court, says Fitbit's sleep claims violate California unfair competition laws and false advertising laws, as well as federal warranty law.

Fitbit didn't immediately respond to a request for comment on the case, which was first reported by The Recorder.