Sleeping well is more important than we think. In fact, a restful sleep not only improves energy, mood, memory and concentration during the day, but also protects the brain from the risk of Alzheimer's, functioning as a real reserve of resources that neurons can draw on to counteract neurodegeneration. But let's try to understand better by analyzing the data of a very recent study published in the BMC Medicine journal by a group of American scientists from the University of California (Zavecz et al, BMC Medicine, May 2023).
What happens in the brain as the years go by
Over the years, particular aggregates of proteins, called beta amyloids, can accumulate in the brain. These aggregates are a hallmark of Alzheimer's but are not sufficient to trigger neurodegeneration. In fact, even in healthy people and with a cognitive function that does not show signs of deterioration, similar aggregates can be found. So what makes the brain more or less sensitive to these protein aggregates? How can we explain that people with the same amount of protein accumulated between neurons also show very different degrees of memory and cognitive function? Science has shown that for cognitive impairment to occur, other factors must intervene, such as neuroinflammation. But it has also been shown that some modifiable factors can create a sort of reserve on which the brain can draw to recover the resources necessary to counteract neurodegeneration, making neurons more resilient and reducing inflammation. One of these factors is sleep and, in particular, the duration of one of its phases, namely that of deep sleep.
The importance of good sleep against Alzheimer's, the study
Scientists recruited 62 adults, average age 75 and all healthy. The volunteers underwent PET to evaluate the presence of beta amyloid aggregates and what emerged was that, despite the absence of Alzheimer's, half had high accumulations of this protein. Then, the volunteers were asked to spend the night in the laboratory in order to be able to monitor their sleep and, in particular, the duration of the deep, or non-REM, sleep phase, considered of great importance for the purposes of the study, since it is the stage of sleep in which the brain regenerates. The following day, the volunteers underwent a memory test in which they were asked to associate names with proposed faces. Among the volunteers who had high accumulations of beta amyloid proteins, those who had a disturbed night, with awakenings and short deep sleep phases, also had a lower score than those who had better sleep and longer deep sleep phases. Deep sleep therefore acted as a reserve for the brain by offering compensatory resources in order to protect cognitive function and memory. Instead, among those who did not have accumulations of beta amyloid proteins, no differences were observed in memory tests between those who had longer phases of deep sleep and those who instead had shorter phases of deep sleep. However, this was an expected result, since in the absence of amyloid beta proteins it is not necessary to provide resilience factors as cognitive function is intact.
How to ensure quality sleep
A restful sleep has more and longer deep sleep phases in a single night. In order to improve the quality of sleep it is important to keep physically and mentally active during the day, to avoid consuming abundant and heavy meals as well as drinks containing caffeine in the evening hours, to keep the bedroom dark and cool. Not only that, even taking a warm shower before going to sleep has been shown to improve the quality of sleep and promote deep sleep. In addition to this, diffusing some essential oils, such as lavender oil, into the room or inhaling them from a handkerchief placed near the pillow has been shown to reduce falling asleep times and promote deep sleep. A particular synergy given by the essential oils of lavender, bergamot and ylang ylang has been shown to improve the quality of sleep and to make sleep more restful and regenerating (McDonnell et al, J Altern Complement Med, 2019).
Other tips to counter Alzheimer's
There are other modifiable factors, which depend on our choices, which can create a reserve of resources for the brain and make it more resilient to toxic conditions for neurons. For example, studying and getting information, at any age, but also practicing moderate physical activity and taking care of social relationships have been shown to counteract dementia. Finally, diet can help, especially when it comes to counteracting neuroinflammation. In this case, a diet as close as possible to the Mediterranean diet, with a high intake of fruit and vegetables, whole grains, legumes, dried fruit and fish, such as anchovies, sardines and salmon, has been shown to be neuroprotective.