Changes in Sleep with Age

Age-related changes in the functioning of the human body, including the nature of sleep, are an irreversible process. It is important to distinguish between natural changes and pathological disturbances.

In November 2017, a group of authoritative experts published the article called Sleep in Normal Aging based on the information resource of the National Institute of Health (NIH). The article thoroughly examines the characteristics of sleep in older people, regardless of possible diseases or medication. Researchers paid attention to the following main characteristics:

•  Sleep duration

Scientific studies confirm that in healthy people ages 20 to 60, both average nighttime sleep and total sleep time per night decrease over time by about 8-12 minutes per decade, and this trend is more pronounced in women than in men. After the age of 60, the duration of sleep, as a rule, remains constant.

•  Sleep initiation

The time it takes to fall asleep (sleep initiation) increases with age for many people, and this can be a concern. However, doctors, based on scientific research, believe that such changes in sleep are natural and not pathological. The same applies to the ability to fall asleep after nocturnal awakenings, which may become more frequent.

The duration of time necessary to fall asleep and the initial most superficial sleep (latent period of sleep) is unchanged from 30 to 50 years, and then increases. Such data was obtained as a result of an analysis of the sleep of 258 people ages 17 to 91. However, the quantitative characteristics of the changes are not given. According to other studies, “sleep latency does increase with age, but the magnitude of the change is very modest.” It is noted that healthy elderly people in most cases retain the ability to resume sleep after nocturnal awakenings.

•  Sleep efficiency

The authors of the publication point out that sleep efficiency, i.e. the ratio of the time during which a person actually sleeps to the total time allotted for sleep, continues to gradually decline after the age of 60, which distinguishes it from other characteristics that remain constant.

•  Sleep stability

The analysis carried out by experts confirmed a trend towards an increase in the number of night awakenings in people from 30 to 60 years old, and an increase in the time to fall asleep again, by about 10 minutes per decade. After the age of 60 these sleep parameters stabilize.

•  Stages of sleep

Science has established that human sleep is cyclical and, at normal duration, includes from four to six cycles, each of which contains two phases - slow and fast. During the slow phase, which accounts for about 75%, the heart rate decreases, blood pressure and body temperature decrease, the body rests and stores energy. The fast phase is characterized by rapid eye movements, fluctuations in pulse, pressure, respiration rate, a person sees dreams. In this phase, the brain is actively functioning, processing and sorting the information received during wakefulness. The duration of sleep stages slightly decreases with age, but it is considered natural.

•  Daytime sleep and daytime sleepiness

Studies show that older people sleep more during the day than younger people: they are usually less busy with work, they have less physical and social activity, and have more time and desire to take a nap during the day. Climatic conditions and traditions play a role: people living in the Mediterranean, China, and Latin America love to sleep in the afternoon.

The research and recommendations of NASA (National Aeronautics and Space Administration) which were published in “Inc.” – a popular American business magazine – in February 2020 are of particular interest. According to this research, pilots who slept at the workplace for 26 minutes had a 54% increase in concentration and 34% overall efficiency compared to colleagues who didn't sleep. “Short naps improve mood, memory, alertness, productivity, and responsiveness,” says Kimberly Cote, professor of psychology and neuroscience at Brock University (Brock University, St. Catharines, Ontario, Canada). However, according to Professor Cote, long and deep sleep during the day, “will contribute to lethargy, also called sleep inertia, that occurs upon awakening and can disturb nighttime sleep.” To get the most benefit from daytime naps, NASA recommends taking 10–20-minute naps, which is enough to restore performance and cognitive function.

Researchers warn of the need to distinguish between the desire to get some afternoon sleep and excessive sleepiness, which can be a sign of cardiovascular disease, depression, cognitive impairment, and other serious malfunctions of the body.

Age-related changes in circadian rhythms

The authors of the article on The NIH analyze circadian rhythms - the internal biological clock that determines cyclical changes in the functioning of the body during the day, including sleep and wakefulness. In older people, this mechanism is less stable, the sleep schedule shifts: a person goes to bed earlier in the evening and wakes up early in the morning. In addition, older people have a harder time adjusting to jet lag or working at night.

With age, the circadian rhythms of the body's production of many hormones change, and this also affects the quality of sleep. In particular, melatonin production decreases, cortisol levels rise at night, which leads to a decrease in the proportion of slow sleep and frequent awakenings in older people.

Summary

Natural age-related changes in sleep parameters should be distinguished from serious disorders that can be caused by numerous factors: general deterioration in health, mental illness, negative changes in lifestyle, negative environmental influences.

The article Sleep in Normal Aging deals with the normal aging of apparently healthy people. According to experts, “there is no doubt that sleep changes with age.” Throughout a person's life, the duration and effectiveness of night sleep gradually decreases, the depth of sleep decreases, and the number and duration of night awakenings increase. Older people tend to go to bed earlier in the evening, get up earlier in the morning, and like to take a nap during the day. Their circadian rhythms become less stable, and the secretion of sleep-related hormones changes. But by the age of sixty, most sleep parameters stabilize, and remain virtually unchanged in healthy people in the future.