When we do sleep, we also dream; in fact, during a typical lifetime, people spend an average of six years dreaming. (aaas.org)
Each computer run simulated the cat population over 6,000 days (a number greater than the typical lifetime of a feral cat), tracking individual cats on a daily basis. (sciencedaily.com)
The last two depend on culture or sociology: the fraction of civilizations that do communicate over interstellar distances and the typical lifetime of the communicating technology.» (scientificamerican.com)