The average adult requires 7 to 8 hours of sleep daily. According to the National Sleep Foundation (NSF) 2005 Sleep in America Poll, 40% of the respondents reported <7 hours of sleep on weekdays. The survey also noted that 14% of Americans perform shift work that goes against the body's natural circadian rhythm. Moreover, most diets contain a great deal of caffeine, which remains in the body for an average of 3 to 5 hours but can continue to affect individuals for up to 12 hours.
Another NSF poll found that 36% of the 1000 Americans surveyed reported a current sleep problem, 27% reported occasional insomnia, and 9% reported chronic insomnia. On average, the individuals with occasional insomnia had had difficulty sleeping for 9.3 years, compared with 13 years for individuals with chronic insomnia.Work-related stress was the most frequent reason for insomnia among individuals with occasional insomnia. Family-related stress, however, was the most common cause for individuals with chronic insomnia.