A nano nap is a period of sleep which lasts between 15 and 30 seconds. It is generally involuntary, and often occurs when people are incredibly tired and bored. Many office workers and students are familiar with the concept, thanks to falling asleep during meetings and classes.
He was caught taking a nano nap during the conference call.
Although napping in general is believed to be beneficial, the benefits of the nano nap are dubious, since one is generally not asleep long enough to truly relax. In fact, since one usually feels guilty and stressed when waking up from a nano nap, it is entirely possible that the nap may actually make the napper feel worse.