Researchers at the Brigham & Women's Hospital, Boston , have reported in the journal Sleep that advancing age is linked with increased sleep disturbances, largely due to breathing problems. Using sleep lab results, they analyzed the frequency of respiratory disturbances in 163 healthy individuals, establishing what they called a respiratory disturbance index, or RDI. About 5% of the under-50 healthy subjects had an RDI of 15 events per hour, whereas over half those over 65 years of age had this RDI level or greater - quite a dramatic increase.

These subjects had no physical signs or symptoms of obstructive sleep apnea, and the authors of the study felt that the high frequency of raised RDI with age was a consequence of the normal aging process. They couldn't say whether those with a high RDI would proceed to develop symptoms of sleep apnea or not.

Because of this uncertainty, and the consequences of untreated sleep apnea - high blood pressure, right-sided heart failure, stroke, abnormal heart rhythm - some experts might recommend treatment for the RDI even when there are no symptoms.

The best treatment for obstructive sleep apnea is continuous positive airway pressure, known as CPAP. An apparatus provides a steady stream of pressurized air top patients through a mask that they wear during sleep. This keeps the airway open during sleep, allowing full oxygen entry. Maybe one way to decide the clinical relevance of high RDI levels in older people might be to measure blood oxygenation levels at annual intervals.