Anxious Personality Predisposes to Sleep Disturbance After Major Stress

TURKU, Finland, Nov. 1 -- People who tend to experience daily life as highly stressful may be more likely to develop sleep problems when traumatic events occur, researchers found.However, the 1.5- to three-fold increased risk may persist only for the first months after a stressful event, such as divorce or family illness, reported Jussi Vahtera, M.D., of the Finnish Institute of Occupational Health here, and colleagues in the November 1 issue of the journal SLEEP.
Action Points
Explain to interested patients that their daily experience of anxiety may impact their sleep after a major stressful event.
Inform patients that the study did not look at whether treating an ingrained tendency toward anxiety or sleep disturbance could impact the effects of a major stressful life event.
These findings from a large, population-based study provide prospective evidence that people who are anxious by nature are predisposed to sleep disturbances, the researchers said.
They analyzed data from the longitudinal Health and Social Support study with a representative sample of the Finnish population. The analysis included 19,199 respondents who completed a survey both at baseline in 1998 and five years later.
At baseline, participants fell into four age groups -- 20 to 24, 30 to 34, 40 to 44, or 50 to 54 -- and 13% reported sleep disturbances. At follow-up, 11% reported new-onset sleep disturbances.
Liability to anxiety, indicated by a general feeling of stressfulness (as measured by the Reeder stress inventory) and symptoms of sympathetic nervous system hyperactivity, was strongly linked to disturbed sleep, the researchers said.
Men and women with the highest levels of general stress on a day-to-day basis were 2.4 times more likely to develop new-onset sleep disturbances compared with those in the lowest quartile (95% confidence interval 2.0 to 2.7). For symptoms of sympathetic nervous system hyperactivity, the odds of developing sleep disturbances were 2.2 times higher for those in the highest quartile than for those in the lowest quartile (95% CI 1.9 to 2.5).
Anxiety also increased risk for persistent sleep disturbances.
Respondents with the most symptoms of sympathetic nervous system hyperactivity were 1.5 times more likely to have sleep disturbances that persisted from baseline through five-year follow-up than those in the lowest quartile of this measure of anxiousness (95% CI 1.2 to 1.8).
Stressful events appeared to trigger problems sleeping, particularly for those who reported a high liability to anxiety.
From baseline to six months before the five-year follow-up, 13,180 participants reported a severe stressful event, such as death or illness in the family, divorce or separation, financial difficulties, or emotional, physical, or sexual violence. Participants who reported events related to changes in their health, which could impact sleep, were excluded.
Another 5,642 patients had a major stressful event in the six months before the follow-up. Among them, 71% experienced one event, 20% reported two events, and the remainder had up to eight events.
For participants who did not have pre-existing sleep problems, cumulative exposure to stressful events linearly increased with risk of sleep disturbances and was about double the risk of unexposed participants whether the events were recent or not.
The association did not appear to be entirely explained by controlling for anxiety and other predictors of sleep disturbances, which reduced the associations by no more than 33% to 39%, the researchers said. Nor were the associations explained by depression.
Death or illness in the family, divorce, and financial difficulties were independent predictors of new-onset sleep disturbances over the longer term, whereas financial difficulties were independently associated with sleep over the shorter term.
For men and women with pre-existing sleep disturbances at baseline, stressful life events were also associated with a 1.6- to two-fold increase in risk of persistent sleep problems at the five-year follow-up, "but only if the event had occurred within six months," the researchers noted.
Anxious people who experienced stressful events had the greatest likelihood of sleep disturbance over the short term.
For men who reported a negative life event, the odds were 3.11 times higher for those with a high general feeling of stressfulness (95% CI 1.90 to 5.10) and 2.88 times higher for those with sympathetic nervous system hyperactivity (95% CI 1.69-4.91) than for those with no exposure to stressful life events.
By comparison, severe life events did not increase likelihood of new-onset sleep disturbance among men not prone to anxiety.
For women in the study, liability to anxiety in combination with stressful events in the prior six months raised the risk of new-onset sleep problems 1.54- to 2.38-fold (95% CI 1.07 to 4.13).
Although acute sleep problems may increase risk of chronic sleep disturbances, liability to anxiety was not linked to sleep disturbance and life events long term (P>0.10).
"This heightened vulnerability was evident, however, only zero to six months after the event," Dr. Vahtera and colleagues wrote.
Dr. Vahtera and a co-author reported support from the Academy of Finland.Primary source: SLEEPSource reference: Vahtera J, et al "Liability to Anxiety and Severe Life Events as Predictors of New-Onset Sleep Disturbances" SLEEP 2007; 30: 1449-1458.