It often happens that the quality of sleep deteriorates significantly as we age. According to a recent study, this phenomenon is caused by the progressive loss of a class of neurons specialized in the control of wakefulness.
Many older people have trouble sleeping normally, with their sleep being marked by difficulty falling asleep, frequent awakenings, and shaky sleep. The impact of this fragmented sleep is far from negligible, since it is estimated that a 70-year-old person sleeps on average about an hour less per night than when they were 20 years old. In addition to being associated with greater fatigue and reduced alertness, several studies suggest that this lack of sleep increases the risk of developing certain diseases such as type 2 diabetes, certain cardiovascular disorders and heart disease. – cognitive blink. Identifying the mechanisms that are responsible for this loss of sleep during aging could therefore have enormous implications for the health and well-being of the elderly.
Loss of sleep neurons
The sleep/wake cycle is largely controlled by what is called the “ventrolateral preoptic nucleus (VLPO)”, a small group of neurons located in the hypothalamus.
When we sleep, these neurons secrete inhibitory neurotransmitters (GABA, galanin) which block the activity of other neurons involved in wakefulness, which keeps the brain immersed in sleep. According to the results recently obtained by scientists from Harvard and Toronto universities, the appearance of fragmented sleep during aging could be caused by a marked decrease in the number of these sleep neurons.
These scientists analyzed data collected from 1000 people aged 65 and over, and followed until their death. First, the sleep quality of these people was assessed using an actigraphic recording (a device that measures a person’s movements) and the results obtained were then correlated with the number of neurons of the VLPO nucleus observed in the brains of the subjects after their death.
The results are unequivocal in patients not suffering from Alzheimer’s disease, the number of VLPO neurons was inversely correlated with the amount of sleep fragmentation, that is to say that the fewer there were of these neurons, the worse the quality of sleep. This association is even more striking in people affected by Alzheimer’s disease and it is likely that the disappearance of these sleep neurons is responsible for the fragmented sleep specific to these patients.
Some tips to preserve your sleep
Identifying the VLPO nucleus as a site of sleep control is important, as it would allow the development of new therapeutic approaches specifically targeting this region of the brain to counter sleep deterioration in the elderly.
In the meantime, it should be remembered that the quality of sleep can be influenced by several aspects of lifestyle, even at a later age. Older people who lead active lifestyles, such as doing regular physical exercise like walking or gardening, generally sleep much better than those who are sedentary. Reducing caffeine, alcohol, and eliminating heavy late-night meals can also contribute to better sleep.
Lim AS et al. Sleep is related to neuron numbers in the ventrolateral preoptic/ intermediate nucleus in older adults with and without Alzheimer’s disease. Brain.
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