It's official. Getting the recommended 7-9 hours of sleep a night is currently out of reach for almost one-third of the population as experts found 31% of adults had average sleep durations outside the recommended range. The global study of thousands of adults found only 15% of people slept the recommended 7-9 hours for five or more nights per week -- and among those who did achieve an average of 7-9 hours per night over the nine month monitoring period, about 40% of the nights fell outside the ideal range.