Epidemiology of insomnia, depression, and anxiety.

STUDY
OBJECTIVES: This study used empirically validated insomnia diagnostic criteria to compare depression and anxiety in people with insomnia and people not having insomnia. We also explored which specific sleep variables were significantly related to depression and anxiety. Finally, we compared depression and anxiety in (1) different insomnia types, (2) Caucasians and African Americans, and (3) genders. All analyses controlled for health variables, demographics, organic sleep disorders, and symptoms of organic sleep disorders.
DESIGN: Cross-sectional and retrospective. PARTICIPANTS: Community-based sample (N=772) of at least 50 men and 50 women in each 10-year age bracket from 20 to more than 89 years old. MEASUREMENTS: Self-report measures of health, sleep, depression, and anxiety.
RESULTS: People with insomnia had greater depression and anxiety levels than people not having insomnia and were 9.82 and 17.35 times as likely to have clinically significant depression and anxiety, respectively. Increased insomnia frequency was related to increased depression and anxiety, and increased number of awakenings was also related to increased depression. These were the only 2 sleep variables significantly related to depression and anxiety. People with combined insomnia (ie, both onset and maintenance insomnia) had greater depression than did people with onset, maintenance, or mixed insomnia. There were no differences between other insomnia types. African Americans were 3.43 and 4.8 times more likely to have clinically significant depression and anxiety than Caucasians, respectively. Women had higher levels of depression than men.
CONCLUSION: These results reaffirm the close relationship of insomnia, depression, and anxiety, after rigorously controlling for other potential explanations for the relationship.