A new study has ranked U.S. states by residents' sleep problems and daytime fatigue. Among the sleepiest states, likely a reflection of the lack of quality sleep, were West Virginia, Oklahoma, Mississippi and Alabama.

The researchers, including Michael Grandner of the University of Pennsylvania, analyzed data from 157,319 participants who had answered two questions about how many days over the prior two weeks (from zero to 14) they had trouble falling asleep, staying asleep or sleeping too much. They also reported the number of days they felt tired or had little energy during that time. [5 Things You Must Know About Sleep]

The study, which relied on information from the 2006 Behavioral Risk Factor Surveillance System, included 33 U.S. states as well as the District of Columbia, Puerto Rico and the U.S. Virgin Islands. The researchers chose a cutoff of six out of 14 days to indicate sleep disturbance and daytime fatigue.

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States with the highest sleep disturbance: (percent of individuals who reported six or more days of sleep issues)

  1. Delaware: 7.2 percent
  2. Virgin Islands:  12.9
  3. North Dakota: 14.6
  4. Hawaii: 15.4
  5. D.C.: 16.6
  6. Iowa: 16.6
  7. Minnesota: 16.7
  8. Wisconsin: 16.9
  9. New Hampshire: 17
  10. Virginia:  17
  11. California: 17.1
  12. Montana: 17.1
  13. Wyoming: 17.2
  14. Vermont: 17.4
  15. South Carolina: 17.8
  16. Maine: 17.9
  17. Texas: 18.2
  18. Puerto Rico: 18.2
  19. New Mexico: 18.4
  20. Oregon: 18.8
  21. Georgia: 19.1
  22. Alaska: 19.2
  23. Florida: 19.6
  24. Tennessee: 19.6
  25. Indiana: 19.7
  26. Rhode Island: 19.8
  27. Nevada: 20
  28. Michigan: 20.4
  29. Louisiana: 20.8
  30. Utah: 21
  31. Missouri: 21.3
  32. Arkansas: 22.1
  33. Alabama: 22.3
  34. Mississippi: 22.4
  35. Oklahoma: 24.7
  36. West Virginia: 26

Sleepiest states: (percent of individuals with daytime fatigue for six or more days)

  1. Virgin Islands: 16.4 percent
  2. California: 17.9
  3. North Dakota: 18.1
  4. D.C.: 18.2
  5. Minnesota: 18.7
  6. Alaska: 18.8
  7. New Hampshire: 19
  8. Vermont: 19
  9. Wisconsin: 19.2
  10. Montana: 19.3
  11. Iowa: 19.4
  12. Puerto Rico: 19.4
  13. Oregon: 19.7
  14. Hawaii: 19.9
  15. Florida: 20.3
  16. Virginia: 20.3
  17. Maine: 20.6
  18. Wyoming: 20.6
  19. Texas: 21.1
  20. New Mexico: 21.6
  21. Rhode Island: 21.6
  22. Georgia: 22.2
  23. Michigan: 22.2
  24. Nevada: 22.6
  25. Indiana: 23.1
  26. South Carolina: 23.2
  27. Delaware: 23.5
  28. Utah: 23.8
  29. Tennessee: 24.4
  30. Missouri: 25.2
  31. Louisiana: 25.4
  32. Arkansas: 26.8
  33. Alabama: 27.1
  34. Oklahoma: 27.7
  35. West Virginia: 29.9
  36. Mississippi: 30

The study is detailed in the current issue of the Journal of Clinical Sleep Medicine.