Regular naps may help slow cognitive decline, including in orientation, language and memory, new research suggests

Sleep accounts for nearly 1/3 of a person's life, and its quality is related to a person's health. In a sense, the quality of sleep even determines the quality of life . However, in modern society, with the accelerated pace of work and life, coupled with the interference of various entertainment activities, few people can get enough sleep.

Not only that, naps, as an important part of the natural sleep cycle, are being abandoned, ignored or even forgotten by more and more people. In fact, naps can not only make up for the effects of insomnia at night, but also eliminate the tension and irritability caused by work, and keep people in a good mood.

Recently, researchers from the Department of Geriatrics at the Wuhu Fourth People's Hospital in Anhui, China, the Department of Geriatric Psychiatry at the Shanghai Mental Health Center, and the Shanghai Jiao Tong University School of Medicine published a study suggesting that regular naps may be associated with better mental agility.

The research team found significant differences in cognitive function and blood lipid levels between nappers and non-nappers in the elderly population of China, suggesting that napping may be associated with better cognitive function, including orientation, language fluency and memory.

The related research, titled "Relationship between afternoon napping and cognitive function in the ageing Chinese population", was published in General Psychiatry, a journal of the British Medical Journal (BMJ).

Napping, Cognition, and Alzheimer's

During human evolution, napping may have emerged as a way to avoid midday heat waves.

But today, naps have become an important part of the human sleep cycle. Not only that, research shows that naps are the most efficient form of sleep, and are a manifestation of biological rhythms, essential for the body to stay awake.

It is worth noting that as we age, our sleep patterns change significantly—nap times become more frequent. In other words, the frequency of naps in the elderly is much higher than that in the young.

It has to be said that in contemporary society, as the average life expectancy of humans increases, the prevalence of Alzheimer's disease is also increasing. Dementia patients find it difficult to take care of themselves, which places a great burden on their families and society. What is even more regrettable is that no effective treatment for Alzheimer's disease has been found, and even prevention is difficult to achieve.

In this regard, lifestyle has a great impact on the development of cognitive function. Previous studies have shown that nighttime sleep disorders are closely related to cognitive decline and increased risk of dementia.

A 2012 longitudinal, population-based study found that daytime napping was associated with a lower risk of cognitive decline over 2 and 10 years in cognitively intact people over 65 years of age. On the other hand, however, some studies have shown that excessive daytime sleepiness can increase the risk of dementia or cognitive decline.

From this point of view, whether napping is beneficial to delay cognitive decline and dementia in the elderly is still a controversial issue. But in any case, whether the frequency of napping in the elderly affects the incidence of Alzheimer's disease is a study that is worth exploring and may help prevent the occurrence and development of Alzheimer's disease.

Regular naps linked to better mental agility

To explore the relationship between napping and cognitive function in the elderly, the research team conducted a statistical analysis on 2,214 apparently healthy elderly people aged 60 and above living in major Chinese cities such as Beijing, Shanghai and Xi'an.

The researchers defined a nap as a period of at least five consecutive minutes of sleep after a meal, but no longer than two hours. Participants were also asked how often they napped during the week -- ranging from once a week to every day.

The study data showed that a total of 1,534 people took regular naps (nap group) and 680 people did not take naps (non-nap group). All participants underwent a series of health checks and cognitive assessments, including the Mini-Mental State Examination (MMSE) for dementia, the Montreal Cognitive Assessment (MoCA) and the Neuropsychological Battery (NTB). In addition, among all the subjects, 739 people volunteered to undergo lipid tests.

The Alzheimer's screening test consists of 30 items that measure several aspects of cognitive ability and higher-level functions, such as visual-spatial skills, working memory, attention span, problem-solving ability, orientation awareness, and verbal fluency. After the data were collected, the research team analyzed them in a meta-analysis.

By comparing the cognitive scores of the napping group and the non-napping group, the researchers found that the MMSE score of the napping group was statistically higher than that of the non-napping group: the two groups of participants had significant differences in MMSE scores in sense of direction and language function (p<0.01), and in the NTB test, there were significant differences in digit span (F=6.80, p=0.009) and language fluency (F=5.40, p=0.020).

Moreover, in terms of blood lipids, among the 739 participants who underwent blood lipid tests (n=428 in the nap group and n=311 in the non-napping group), there was a significant difference in triglycerides (TG) between the two groups (F=7.307, p=0.001), but there was no statistically significant difference in the levels of total cholesterol (CHOL), high-density lipoprotein (HDL), and low-density lipoprotein (LDL).

In addition, the research team also integrated the relationship between demographics, naps, nap frequency, physiological diseases and cognition. Linear regression analysis showed that there was a significant correlation between gender, age, education level, diabetes, naps and cognitive indicators. This means that naps are associated with better cognitive functions, including positional awareness, language fluency and memory ability.

It’s worth noting that this is an observational study, so it can only confirm that napping helps slow cognitive decline in older people, but it can’t determine the specific reasons for this phenomenon. In addition, it is also impossible to determine whether the length of the nap affects this association - which could be very important.

In this regard, the research team has made some possible explanations for these phenomena: inflammation may be the "middleman" linking naps and health conditions. The researchers pointed out that inflammatory chemicals play an important role in sleep disorders, sleep can regulate the body's immune response, and naps are considered to be an evolutionary response to inflammation.

Overall, this study presented three main findings: first, older adults who napped had significantly improved cognitive abilities compared to those who did not nap; second, higher TG levels were found in older adults who napped; and finally, napping was strongly associated with orientation, language function, and memory.

From this, it can be seen that naps have an important connection with the cognitive ability of the elderly. The aging problem in today's world is becoming increasingly serious. Perhaps we can take the simplest approach - promoting naps, so as to slow down the decline in the cognitive ability of the elderly population and reduce the incidence of Alzheimer's disease!