What is the ruling on deep sleep during working hours, and is that considered a dereliction of trust? Is the salary earned during this period lawful or unlawful?

Sleeping during work is considered a dereliction of duty and trust, and it makes the earned wage unlawful (haram); because it is taking money without exchange or consent.

It is advisable to sleep early to avoid sleeping at work.

If it is impossible to rent a nearby dwelling or perform the agreed-upon work, one must leave this job and search for another that suits one's abilities and whose requirements can be fulfilled; in compliance with the words of Allah Almighty: "O you who have believed, fulfill [all] contracts."