Dr. Avnish Jolly, Chandigarh :Researchers have said that “older people may need less sleep than younger people”, The Daily Telegraph reported lat week. It said that a US study had found that when people were told to sleep for 16 hours a day for several days, those aged between 60 and 72 years managed an average of 7.5 hours sleep compared to nine hours amongst the 18-32 year-olds.
The study also found that most of the younger subjects slept much longer during the study than they normally did, which suggested that they usually did not get enough sleep. Dr Elizabeth B. Klerman from the Division of Sleep Medicine at Brigham and Women’s Hospital, Harvard Medical School in the US and and Derk-Jan Dijk from the Surrey Sleep Research Centre at the University of Surrey in Guildford carried out the research. The study was funded by grants from the National Institutes of Health, Biotechnology and Biological Sciences Research Council and the Wellcome Trust. The study was published as a report in the peer-reviewed medical journal Current Biology.
This study does not provide firm conclusions for why this difference occurs, nor does it define what a “need” for sleep is. However, as the researchers acknowledge, the fact that older healthy people sleep less than younger healthy adults is more simply explained by a reduced need, as opposed to a reduced ability to sleep. For all ages, getting enough sleep is important, as not enough can affect mood, alertness and performance at school and work.
It tested and compared various aspects of sleep in 18 older subjects (12 men and six women between 60 and 76 years old) and 35 younger subjects (17 men and 18 women between 18 and 32 years old). All the recruits were healthy and had a full medical, including an examination, electrocardiogram and laboratory tests of blood and urine, which verified the absence of any known sleep disorders. None of the recruits were taking prescription or non-prescription medication, had travelled out of their local time zone within the past three months or worked night shifts in the last three years. All health food supplements, caffeine, alcohol and tobacco were banned in the three weeks prior to the start of the study.
The participants’ usual sleep habits were recorded for three weeks at home, through a daily diary and by telephone calls to a time-stamped machine. This produced a measure of the participants habitual sleep duration (HSD), which was the time they spent in bed (this included periods when they were awake). This HSD was used to schedule the duration and timing of the participants’ sleep periods when they were admitted to a sleep lab.
On the first night in the sleep lab, the participants were scheduled to sleep the duration and time dictated by their HSD. The following day, the participants took part in a multiple sleep latency test (MSLT), that began two hours after waking, and was repeated five times in two hour intervals. The MSLT is a validated tool that measures how easy it is for subjects to lapse into the early phases of sleep when instructed. They are awakened when certain sleep criteria are met, and if they do not manage to sleep within a 20-minute period, then each test is terminated.