Variability in how long a person sleeps and when he or she goes to bed and wakes up, is independently associated with an elevated risk for suicide, according to a study presented June 8 at SLEEP 2010, the 24th annual meeting of the Associated Professional Sleep Societies LLC, and reported by Medical News Today.

Sleep disturbances are a defining symptom of depression. Some people sleep too much, while others sleep too little. Still others have a mix of sleep disruption, with insomnia on some nights and excessive sleep on other evenings. There have been few studies, however, to determine whether disrupted sleep is associated with the risk of suicide.

To determine the impact of sleep on suicide risk, researchers conducted a three-week study on 49 actively suicidal undergraduate students at Stanford University, in Palo Alto, California. The team, led by Rebecca Bernert, PhD, a fellow in the Department of Psychiatry and Behavioral Sciences, tracked the participants’ sleep using a sensor that can be worn like a wristwatch. This provided Bernert’s team with an accurate measure of study participants’ sleep patterns: when they went to sleep, when they rose, and how many total hours they slept in a 24 hour period. Suicidal and depressive symptoms were tracked before the study started and then one and three weeks after study initiation.

Bernert and her colleagues found that all measures of sleep disturbance were linked to more severe symptoms of suicidal thoughts and behaviors. After controlling for depression, however, the only sleep-related factor that predicted greater suicide risk was variability in a person’s sleep.

“Compared to other suicide risk factors such as a past suicide attempt, disturbed sleep is modifiable, often visible and amenable to treatment,” Bernert said. “In this way, the study of sleep may inform suicide risk assessment and represent a clinically unique opportunity for intervention.”