by Ross Walker
It is estimated that a third of the world’s population suffer a degree of insomnia. As we age and especially beyond 50, our sleep becomes more fragmented but strangely more efficient.
Typically, adults go through five cycles of sleep lasting around 90 minutes. Within each cycle, there are five phases. It is during phase three and four which are the deeper phases of sleep, where the cells of the body are rested and rejuvenated. Phase five sleep is dream sleep, which is why we typically dream just prior to waking up.
People in their seventies compared with people in their twenties, have at least one hour less sleep per night, which may be one of the reasons why we feel more tired as we age. This is a good reason to encourage an afternoon nap. There was a study of 23,000 Greeks showing those who had an afternoon sleep, had a 40 per cent lower rate of cardiovascular disease.
Loss of sleep leads to cognitive dysfunction (problems with thinking), higher blood pressure, all forms of vascular disease and Type II diabetes.
Professor Saper from Harvard University has been researching sleep for over 20 years and there have been two major discoveries which may lead to developing better therapy to improve sleep as we age.
Professor Saper’s group has recently discovered a sleep switch in the ventrolateral preoptic nucleus of the hypothalamus, which is responsible for switching off the brain’s arousal system, leading to droping off to sleep rapidly. When 50 per cent of the nerves in this area were lost, the sleep time was cut by 50 per cent and much more fragmented and disrupted.
The human brain has a similar group of cells known as the intermediate nucleus and it appears to work the same as it did in the experimental animals.
Following on from this study was the long term ageing and dementia study known as the “Rush memory and ageing project” of 1000 healthy 67-year-olds which commenced in 1997.
Since 2005, some also had their activity monitored every two hours for at least a week to 10 days, including their sleep intervals. Autopsies were performed on forty five of these patients who died at age 89 and a strong link was found between poor sleep and disruption in this intermediate nucleus in the hypothalamus.
There is a clear link between lack of neurones in this area and sleep fragmentation. The researchers are now working on developing specific treatments to block the neuronal loss and therefore improve the release of the chemicals in this region.
A second study has found another area in the brain stem, which is the area of the brain at the base of the skull known as the 'parafacial zone'.
There is a particular neurotransmitter in this area known as 'GABA' which induces deep sleep. The researchers found that when a particular viral based chemical was introduced in this area, it switched on the GABA neurones and the animals quickly fell into a deep sleep without the need for sedatives or sleep aids.
Both these key pieces of research show clearly we are getting closer to understanding the mysteries of sleep and how we can improve sleep in all people. Research around the world has shown clearly that having seven to eight hours good quality sleep every night, is as good for your body as not smoking.
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