by Cesare Peccarisi
Fragmented and shallow sleep, that is, sleep with frequent nocturnal awakenings, doubles the risk of reduced cognitive performance. A compass to improve prevention therapies by taking care of the hours of rest
In 2013, a study on 145 middle-aged subjects published in JAMA Neurology by Washington University in Saint Luis was the first to place emphasis on alterations in the quality of sleep rather than its quantity in relation to the risk of developing cognitive impairment.
I study
In the meantime, there have been dozens of studies on the correlations between sleep disorders and dementia and now in Neurology comes that of researchers from the Universities of San Francisco and Chicago directed by Yue Leng which confirms the results of 11 years ago only up to a certain point, placing a caveat on the altered subjective perception that patients have of their night’s rest. American researchers used 7 neuropsychological scales to evaluate how patients subjectively perceived their morpheic disorder. They studied 526 middle-aged (between 30 and 40 years old) of both sexes, both white and black, who slept on average about 6 hours a night (between 5 and 7.2) and then re-evaluated them 11 years later. They thus saw that the subjective quality of sleep they perceived was not directly associated with cognitive impairment and for an objective evaluation of their night’s rest it was necessary to use the same method as 11 years earlier, i.e. actigraphy, a technique that analyzes it through body movements.
Wrong perceptions
The actigraph can be worn for days or weeks on the ankle or more often on the wrist. Compared to 2013, today there are also various actigraph smartwatches, some recently launched on the market and can be purchased by everyone to have an account of the hours actually slept, of awakenings during the night or of any daytime falling asleep. In the study it was clear that the subjective perception of disturbed sleep was exaggerated: if 45.6% of patients reported this impression, the real sleep fragmentation index recorded by the actigraph was approximately one third (approximately 14%).
The importance of continuous awakenings
however, it is precisely fragmented and shallow sleep, that is, sleep with frequent nocturnal awakenings, that doubles the risk of reduced cognitive performance. The largest proportion of fragmented sleep recorded by the actigraph occurred in overweight black males, mostly with a history of depression and hypertension. Regardless of race and gender, those who suffer from fragmented sleep feel that they sleep little and badly and have repercussions on blood pressure and mood with hypertension and depression, two conditions implicated in cognitive decline. In those who the actigraph recorded the greatest sleep fragmentation in middle age, eleven years later the worst executive functions and the greatest global cognitive impairment were observed, while this association was not observed with the quality of sleep perceived by the same subjects. Therefore, if already in middle age the association between sleep quality and cognition is confirmed as important – comments Liborio Parrino, director of the Neurology Unit and the Sleep Medicine Center of the University of Parma – the use of suitable tools is equally fundamental to objectively evaluate the impact of sleep quality compared to its quantity.
Prevent insomnia
This data further refines the concept that morpheic alterations precede dementia by a long time – says the President of the Italian Society of Neurology Professor Alessandro Padovani of the University of Brescia – and is useful for the prevention of neurodegenerative pathologies through not only pharmacological treatments aimed at ensuring a good quality and quantity night’s rest. Establishing them early, in addition to blocking the circulatory, metabolic and inflammatory alterations that are associated with sleep disorders, offers the advantage of acting without interfering with the therapies used for many neurodegenerative diseases such as Alzheimer’s, so even the treatment of a “simple” insomnia can become one of the objectives to prevent even the most serious and devastating forms of cognitive impairment.
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January 27, 2024 (changed January 27, 2024 | 07:59)
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