Have you returned from lunch to the office and are pecking at your computer?
In Japanese culture, sleep at work is commonplace and is even considered a sign of devotion to the job in the eyes of managers.
The practice of nap at work is called inemuri, and the logic behind it is that the worker probably stayed up late to work or simply worked to exhaustion, so his fatigue is understandable.

source:
https://en.wikipedia.org/wiki/Sleeping_while_on_duty
https://theculturetrip.com/asia/japan/articles/asleep-on-the-job-japans-inemuri-phenomenon/