HOW MUCH SLEEP DO YOU NEED? THE NATIONAL SLEEP GUIDE ON SLEEP VOLUME. How much sleep do the experts suggest you need? Well, it depends! Age, activity, genetics, environment, mental strain & stress, can all determine one's optimum rest time. And, of course, it can change from day-to-day. However, the National Sleep Foundations 'general' guide provides a good reference. Click below for the full report.