How Sleep Changes as We Get Older (and Why)
A 2017 study published in the journal Sleep argued that little is known about how sleep changes over the course of our lives. This prompted researchers to investigate how sleep changes among adults over 20 years and to try and determine what factors influence these changes.
Researchers collected data on participants in five separate rounds between 1987 and 2012. The study included adults who had participated in at least four rounds of data collection. This led to a total study population of 3,695 adults.
How sleep data was collected and categorized
In each round, participants were asked how many hours of sleep they got over a 24-hour period. Those who slept for six hour or less were defined as short sleepers, those who slept for between seven and eight hours were defined as moderate sleepers, and those who slept for nine hours or longer were defined as long sleepers. Sleep quality was measured based on the Pittsburgh Sleep Quality Index.
Measuring sleep duration over 20 years
The study found that just over half (56 percent) of participants enjoyed persistent moderate sleep duration over 20 years. Three percent lived with persistent short sleep duration, while only one percent lived with persistent long sleep duration.
How sleep duration changed over 20 years
Forty percent of participants experienced a change in their sleep duration over the 20-year period. Seventeen percent became short sleepers, 10 percent became moderate sleepers, nine percent became varying sleepers, and four percent became long sleepers.
Risk factors for shorter sleep
The study revealed that those who began to get less sleep as time went on were more likely to be unemployed or blue collar workers. Those who were persistent short sleepers were more likely to be male, 30 years or over, and unmarried.
Persistent short sleep duration linked to poor sleep quality
Perhaps unsurprisingly, those who did not have a persistent moderate sleep duration over 20 years were more likely to complain about sleep quality. At the end of the 20-year period, 58.4 percent of persistent short sleepers reported frequent nighttime awakenings and 44.3 percent reported finding it difficult to fall asleep after awakening.
The decline in sleep duration
This study found that sleep duration changed for nearly half of all participants and more than one in six participants became short sleepers over the course of 20 years. Its authors suggested that today’s 24/7 "switched-on" society may be partly to blame. However, previous studies that have set out to investigate this theory have reported mixed results. So, what’s going on?
Changes in sleep may be entirely natural
As pointed out by the authors of the study, sleep duration naturally becomes shorter as we get older and this is part of the natural aging process. Our circadian rhythm tends to get weaker as we age and additional health issues (and medications) can also affect sleep. Since this study followed participants over 20 years, it likely captured these natural age-related changes in sleep.
The importance of good health and exercise
Perhaps the most interesting finding of this study was its identification of poor self-rated health and leisure-time physical inactivity as being consistently linked to almost every change in sleep. This emphasizes the importance of good health and exercise on long-term sleep duration and sleep quality.