So say Paul Peppard, PhD, and colleagues from the University of Wisconsin-Madison in the Archives of Internal Medicine.
The study supports the theory that breathing problems during sleep (sleep-related breathing disorder) may be a cause of depression, and doctors should keep that in mind, Peppard's team notes.
The researchers studied about 1,400 Wisconsin adults for up to 16 years.
Participants were 30-60 years old (average age: late 40s to mid-50s).
Every four years, participants did three things:
- Spent a night at the University of Wisconsin-Madison's sleep lab.
- Completed a depression questionnaire.
- Reported any medicines they were taking, including antidepressants.
Over 16 years, they completed a combined total of about 3,200 sessions at the sleep lab.
During those sessions, the researchers counted how many times each participant had breathing problems during sleep.
Breathing Easy... or Not
About 330 participants had no breathing problems during sleep.
The rest of the participants fell into three groups:
- Minimal sleep-related breathing disorder (less than 5 hourly events)
- Mild sleep-related breathing disorder (5 to 14 hourly events)
- Moderate to worse sleep-related breathing disorder (at least 15 hourly events)
More than 1,900 had minimal sleep-related breathing disorder. Another 600 or so had mild sleep-related breathing disorder. About 350 had moderate or worse sleep-related breathing disorder.
Even slight cases of sleep-related breathing disorder predicted depression risk, the study shows.
Compared with participants without breathing problems during sleep, those with moderate or worse sleep breathing problems were 2.6 times more likely to become depressed during the study.
The odds were also high for participants with less severe cases of sleep-related breathing disorder.
Compared with sleepers who breathed easily, those with mild sleep-related breathing disorder were twice as likely to become depressed during the study.
By the same comparison, those with minimal breathing problems were 60% as likely to become depressed during the study.
Adjusting for other factors didn't change the results.
In light of the findings, doctors should watch for depression in patients with sleep-related breathing disorder, the researchers write.
SOURCES: Peppard, P. Archives of Internal Medicine, Sept. 18, 2006; vol 166: pp 1709-1715. News release, JAMA/Archives.
By Miranda Hitti
Reviewed by Louise Chang