is the Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

ese practice of sleep
Sleep is a naturally recurring state characterized by reduced or absent consciousness, relatively suspended sensory activity, and inactivity of nearly all voluntary muscles. It is distinguished from quiet wakefulness by a decreased ability to react to stimuli, and is more easily reversible than...

ing on the job
Job (role)
A job is a regular activity performed in exchange for payment. A person usually begins a job by becoming an employee, volunteering, or starting a business. The duration of a job may range from an hour to a lifetime . If a person is trained for a certain type of job, they may have a profession...

. It literally means, "sleeping while present". It is a way to show how committed you are to working. In other words, you spend so much time working that you sleep too little at home and have to do inemuri.