INSOMNIA WATCH

Does Zopiclone Hinder Memory?

At least one insomnia medication affects sleep-associatedmemory function, according to an article published inNeuroscience Research (October 2003). Researchers compared 2sleep therapies: 0.25 mg zopiclone, a nonbenzodiazepine hypnotic,and 7.5 mg brotizolam, a benzodiazepine hypnotic widelyused outside the United States.

In a double-blind, placebo-controlled, crossover study, SouthAmerican patients learned a list of words an hour before takinga single bedtime dose of the study drug and then attempted torecall the words after awakening the next morning. Brotizolamdid not affect word recall, compared with placebo. The patientstreated with zopiclone, however, remembered fewer words,compared with the placebo patients. Interestingly, neither agentwas found to cause residual (next-day) sedation.

Because they may impair sleep-associated memory storage,nonbenzodiazepine "Z drugs" such as zopiclone may requiremore study regarding their effect on cognitive function, memoryprocesses, and sleep function.

Insomnia Patients Are Warmer

As the healthy sleeper falls asleep, heat is transferred fromthe body core to the periphery, resulting in an increase inskin, finger, and foot temperatures.Yet, little has been knownabout this heat transfer process in poor sleepers. Australianresearchers compared finger temperatures in patients withand without insomnia as they initiated sleep. The results ofthe study were reported in the American Journal ofPhysiology: Regulatory, Integrative and ComparativePhysiology (November 2005).

Despite comparable baseline finger temperatures andcontrary to the researchers' expectations, the increases infinger temperatures in the patients with insomnia were significantlyhigher (P = .001), compared with those of thehealthy controls. The researchers noted that the insomniacs'core body temperatures also were significantly higher thanthose of the healthy sleepers. It appears that temperaturesand heat transfer processes differ in those who sleep welland in those who sleep poorly, although the researchersbelieve that this finding requires more research.

Obesity Means Shorter Sleep

Obesity and hormonal changes associated with excessiveweight have previously been associated with short sleep. Nowa recent study reported in the September 18, 2006, issue ofthe Archives of Internal Medicine provides more evidence forthis observation.

A group of 990 patients in Iowa was studied to determinewhether there was a relationship between body mass index(BMI) and short sleep time. Cross-sectional analysis of therural, adult patients found that self-reported sleep durationon weeknights was negatively correlated with BMI. That is,increased body weight was associated with shorter sleeptime. This correlation between high BMI and short sleepremained valid even after adjusting for a variety of keysocioeconomic and health factors, such as sex, age, educationallevel, income, marital status, alcohol use, snoring, anddepression.

Poor Sleep Predicts Suicide

In a study reported in theEuropean psychiatric journalPsychiatria Danubina (September2006), data from theUS National Comorbidity Surveywere assessed to determinethe association betweensleep and suicide.

The researchers employedstatistical analyses to determinewhether average nightlysleep time correlated withsuicidal thoughts and actionsin >8000 adults aged 15 to54. After adjusting for demographicfactors, they determinedthat decreased sleeptime significantly increasedthe odds of suicidal thoughtsand attempts. Mental disordersalso were associatedwith less sleep, as well aswith suicidal ideation andattempts. Yet, these disordersdid not significantly influencethe relationship between lesssleep and suicide.

Thus, poor sleep appears toincrease the likelihood ofboth suicidal thoughts and attempts,even after taking intoaccount the effects of comorbidconditions such as depression.The researchersbelieve that the study resultsmay be used to improve suicide-prevention measures andprograms.