Inemuri (居眠り?) is the Japanese practice of sleeping on the job. Salarymen in Tokyo sleeping on the subway
It literally means, "sleeping while present". It is a way for an employee to show how committed they are to working. In other words, the employee spends so much time working that they sleep too little at home and have to do inemuri. Some people even fake inemuri, so that their bosses believe they are working hard. Unwritten rules apply to inemuri, including who is allowed to do it - only those high up or low down in a company - and how it is performed - the person is supposed to remain upright to show they are still socially engaged in some way.