Assessment of sleep and circadian rhythm disorders in the very old: the Newcastle 85+ Cohort Study.

OBJECTIVES

to examine the association between subjective and objective measures of sleep and wake and other health parameters in a cohort of the very old.

DESIGN

a population-based cohort study.

SETTING

primary care, North East England.

PARTICIPANTS

four hundred and twenty-one men and women, aged 87-89, recruited to the Newcastle 85+ Study cohort.

METHODS

sleep questionnaires were administered and sleep-wake patterns were assessed over 5-7 days with a novel wrist triaxial accelerometer. Associations between sleep measures and various health parameters, including mortality at 24 months, were examined.

RESULTS

only 16% of participants perceived their sleep as severely disturbed as assessed with questionnaire responses. Wrist accelerometry showed marked variation between normal and abnormal sleep-wake cycles that did not correlate with the participants' perception of sleep. Impaired sleep-wake cycles were significantly associated with cognitive impairment, disability, depression, increased falls, body mass index and arthritis but not with any other specific disease markers and with decreased survival.

CONCLUSIONS

commonly used sleep questionnaires do not differentiate well between those with objectively determined disturbance of sleep-wake cycles and those with normal cycles. Abnormal sleep-wake patterns are associated with institutionalisation, cognitive impairment, disability, depression and arthritis but not with other diseases; there is also an association with reduced survival.