Will self-driving cars have steering wheels? Maybe not, if engineers keep falling asleep.

Ford's self-driving cars will skip over Level 3 — where cars are automated, but human drivers are still expected to take over if need be — to Level 4, where cars are basically fully autonomous except for extreme conditions. (Self-driving cars that would meet the requirements for Level 5 are still theoretical at this point.) The levels are defined by the Society of Automotive Engineers, or SAE.

Automotive News reported that Ford came to that decision after its engineers fell asleep, lulled into a false sense of security with nothing much to do while driving Level 3 cars.

“These are trained engineers who are there to observe what’s happening,” Ford Product Development Chief Raj Nair told the publication. “But it’s human nature that you start trusting the vehicle more and more and that you feel you don’t need to be paying attention.”

A spokesman for Ford denied that report, but confirmed the automaker would pursue Level 4 autonomous vehicles.

"Reports that Ford engineers were falling asleep while testing autonomous vehicles are inaccurate," Ford said in a statement. "We believe that high levels of automation without full autonomy capability could provide a false sense of security, and that this presents a challenge for the driver to regain full awareness and control of the vehicle if a situation arises where the technology cannot function. That is why we’re currently pursuing SAE Level 4 autonomous capability that will take the driver completely out of the driving process in defined areas."

Ford invested $1 billion in the autonomous vehicle startup Argo AI earlier this month, so there's big money behind these decisions.

Deciding on Level 4 aligns Ford with Waymo, Google's self-driving project, which also found that human drivers grew inattentive when tasked with only sort of driving.

“Level 3 may turn out to be a myth,” Waymo CEO John Krafcik said, according to Automotive News. “Perhaps it’s just not worth doing.”

Unless you need a nap, that is.