Sleep and its architecture change with age. Many people, as they get older, report feeling like they sleep less. It is not a feeling, it is reality. A well-known meta-analysis published in 2004 in the journal Sleep concluded that total sleep time decreases linearly, at a rate of between 10 and 12 minutes per decade as we age during adulthood until reaching 60 years old, where that time stabilizes. The same study found that the proportion of time we are actually asleep in bed is only about 80% in 70-year-olds, while in adolescence that proportion reaches 95%.
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“This does not mean that we need less sleep, but simply that it becomes more difficult for us to sleep the necessary amount of time,” clarifies Juan Antonio Madrid, professor of Physiology and founder of the Chronobiology and Sleep Laboratory at the University of Murcia. What happens, according to the author of El sueño del Sapiens (Plataforma Editorial), is that with age the time of deep sleep decreases, which increases awakenings and, therefore, sleep fragmentation. On the other hand, adds Dr. Sandra Giménez Badia, clinical neurophysiologist at the Hospital de la Santa Creu i Sant Pau in Barcelona, there is a progressive disruption of circadian rhythms: older people tend to fall asleep earlier and, therefore, also wake up earlier.
These factors, combined with the increased free time typical of retirement, cause the need to take a nap at midday to progressively increase to recharge after an early awakening or to recover lost minutes of sleep during the night. “Basically, what happens with aging is that the clear boundary between nighttime sleep and daytime wakefulness dissolves, becoming more imprecise,” explains Madrid.
There are numerous studies that support the multiple benefits of a short nap, between 15 and 30 minutes. Among them, increases in alertness levels, sustained attention, and reaction time, as well as improvements in mood and subjective feelings of energy. Some studies also seem to point to an association between this short nap, known as an energy nap or power nap, with reductions in blood pressure and stress levels.
However, when naps in older people regularly exceed those 30 minutes or are taken daily in the morning, those benefits are not only lost but may indicate that something is not quite right. A recent study published in the journal Jama Network Open that followed more than 1,300 older adults for 19 years found that longer, more frequent, and morning naps are associated with higher all-cause mortality rates. The strongest relationship was found with morning naps, as individuals who regularly napped in the mornings showed a 30% higher mortality risk compared to those who napped in the afternoon. Each additional hour of napping at any time of day was also associated with about a 13% higher mortality risk.
“Our study is one of the first to demonstrate an association between objectively measured nap patterns and mortality, and suggests that monitoring these patterns has enormous clinical value for early detection of health problems,” said Chenlu Gao, lead author of the study and affiliated researcher at the Sleep and Circadian Disorders Division of the Department of Medicine at Mass General Brigham (Boston, Massachusetts, USA), in a press release.
This idea of clinical value is also emphasized by Sandra Giménez Badia, who reminds that, in no case, can a relationship between napping and mortality be established. “The morning or long nap, in this case, acts as a biomarker, a signal telling us that something is happening underneath, whether it is a circadian rhythm disruption, some cardiovascular disease, or a neurodegenerative disease. In fact, one of the first symptoms of neurodegeneration is increased daytime sleepiness,” she argues.
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In this regard, a study published in 2022 in the journal Alzheimer’s & Dementia found a bidirectional relationship between napping and dementia: on one hand, excessive daytime naps predict a higher future risk of dementia; while, on the other hand, a dementia diagnosis accelerates the increase in daytime naps during aging.
Naps and medical check-ups
“Now that we know there is a strong correlation between nap patterns and mortality rates, we can justify implementing wearable devices to assess daytime naps in order to predict health problems and prevent further deterioration,” the study authors maintain.
Based on the results of the same study, the consulted experts also agree on the importance of primary care doctors asking older people about their sleep and naps during check-ups or any other consultation. “It is inconceivable, with all we already know, that an older person is not asked about their nighttime sleep, schedules, or naps during a medical consultation. This information can alert us early to many things,” says Juan Antonio Madrid.
The professor at the University of Murcia also highlights the importance of being proactive and intervening to improve patients’ sleep patterns. An opinion shared by Sandra Giménez Badia. “One of the things we emphasize most to patients is to try to maintain sleep and daytime activity routines. This applies at any age and condition but is especially important in older people,” notes the member of the Cognition and Sleep working group of the Spanish Sleep Society (SES).
In the same vein, Juan Antonio Madrid stresses the importance of increasing the contrast between day and night. How? By going for a walk or exercising early in the morning, preferably exposing oneself to sunlight, recovering strength at midday with a short nap – if needed – and trying to engage in social life and group activities in the afternoon, whether dancing, a game of chess, or playing with grandchildren. “It is important that the day remains day and that we do not start dozing off out of boredom or because we don’t know what to do,” he concludes.