Asleep or looking at his phone?

[StrayKat]

2. Microsleep.

It looked like an episode of microsleep to me. He may not realize he's done it.

https://en.wikipedia.org/wiki/Microsleep

A microsleep (MS) is a temporary episode of sleep which may last for a fraction of a second or up to 30 seconds where an individual fails to respond to some arbitrary sensory input and becomes unconscious.[1][2] MSs occur when an individual loses awareness and subsequently gains awareness after a brief lapse in consciousness, or when there are sudden shifts between states of wakefulness and sleep. In behavioral terms, MSs manifest as droopy eyes, slow eyelid-closure, and head nodding.[2] In electrical terms, microsleeps are often classified as a shift in electroencephalography (EEG) during which 4–7 Hz (theta wave) activity replaces the waking 8–13 Hz (alpha wave) background rhythm.[3]