How Sleep Patterns Change Over a Lifetime
The older you get, the less you sleep. That’s an overgeneralization, but it is certainly true from birth to age 25 and – unfortunately, elderly people tend to sleep shallower and less than young adults in the same circumstances.
Newborns sleep 16 to 18 hours a day. Half of this is REM sleep and half is slow-wave sleep, with little shallow stage 1 and 2 sleep. By the age of one, children usually sleep 13 to 14 hours with that number decreasing until they reach adolescence. Toddlers typically take afternoon naps prescribed by parents seeking to prevent overtiredness, and the ending of daily naps is seen as a hallmark of maturation for the young child.
As the child grows, time spent in REM declines until it reaches about 90 minutes per night in the mid-teens. Stage 2 sleep increases. Children typically spent a lot of time in slow-wave (Stage 3) sleep which is important for growth. This is why it is so hard to wake kids up during the night. It is hard to awaken anyone from slow-wave sleep but kids spend more of the night in that stage than adults do.
Teenagers generally require at least eight and a half hours of sleep a day. Some experts go so far as to say that teens need more than nine and a half hours each day. With the pressures of academics, athletics, dating, etc., few teens are getting enough sleep these days. Also, teens’ internal biological clocks tend to keep them awake later in the evening and let them sleep later in the morning than adults. They are natural night owls. Some high schools have found that ringing the first bell an hour or so later helps the performance of students. Check out our guide for more info on adolescent sleep needs.
Young adults (late teens, early 20s) have the lowest rate of sleep disturbances of any age group with the possible exception of babies. They are past the common childhood disorders (night terrors, sleepwalking) but do not yet suffer the insomnia of middle age or the fragmented sleep of old age. This is a generalization, of course, but we can say that young adulthood is the golden age of sleep.
By the mid-20s the shift in circadian cycle in the teenage years has subsided. Some people are owls and some are larks, but the adult distribution of chronotypes is established. Most adults need around eight hours of sleep to function well. The government’s Healthy People 2020 initiative uses a goal of 7 hours per night for adults. (For adolescents the goal is 8 hours per night on school nights.) Although many people claim they require less, only 10% require significantly more or less sleep.
Seasons of life
Studies of population groups by socioeconomic status, sex, race/ethnicity, marital status, etc. continue to show age is the biggest demographic factor when it comes to sleep disorders.
For adult women, pregnancy and menopause can cause significant changes in sleep patterns. In the first three months of pregnancy, most mothers-to-be require significantly more sleep than usual and insomnia becomes a problem because of hormone changes. Later in the pregnancy snoring and restless legs syndrome can occur, although these phenomena disappear after the baby is born. Hormonal changes may play a part in why sleep quality declines during menopause. Insomnia, snoring and sleep apnea become more common during these years, perhaps due to the psychological factors associated with menopause or perhaps caused by the aging process and weight gain associated with menopause.
Contrary to the popular belief, the need for sleep does not decline with old age. While the elderly do find that their slumber becomes more fitful, they continue to need about the same amount of sleep that they needed in early adulthood. Experts say that the number of nocturnal awakenings can start to increase as early as the age of 40. Older people more often nap during the day to make up for the lost sleep from the fragmentation at night and because retired people have the opportunity to nap more than working people do. More on insomnia in older people.
Cornell University researchers did a longitudinal study – they followed people for years – and found – no surprise – that people slept shorter times as they got older. The scientists also calculated that both the homeostatic process for sleep regulation and the circadian process declined over time and that the homeostatic process started to decline before the circadian one did.
Jokes abound about lazy teens who seem to sleep all morning and their grandparents who rise before dawn and are in bed in early evening. The stereotypes have grounding in reality, though and are based in biology. It’s not just lifestyle choices of different demographic groups. Scientists have found that the expression of at least some genes associated with the circadian cycle change with age. A paper published in 2015 in the prestigious Proceedings of the National Academy of Sciences announced the finding of a clock mechanism that starts ticking only in the brains of older people.
Scientists found 235 genes that control circadian ryhms in the prefrontal cortex When a person reaches old age, some of these genes essentially shift off – or into low gear where they stop expressing actively. But other genes start expressing and form a new circadian clock – one that is shifted so the individual is more active earlier in the day.
Poor people sleep worse than rich people (weak correlation) and women sleep worse than men, but the transitions from young adult to middle age and from middle age to old age are the biggest inflection points from a public health perspective.
Primitive Sleep Patterns Were Social
Communal sleep is more common in less developed societies than in the technologically advanced West, although it is not clear that this is a cultural preference, conscious choice, or consequence of less space per person in the living quarters.
Discover magazine profiled anthropologist Carol Worthman who studies primitive cultures and sleep practices in them. She thinks that the customs of surviving hunter-gatherer societies shed light on how all humans slept at one time. She described sleep for these people as a “very fluid state” happening whenever the individual feels sleepy. Nighttime sleep is a social activity, in contrast to the isolated environments most modern people spend the night in.
If this idea is true, and the natural way of sleeping is not an uninterrupted block of 7-8 hours, then you have to wonder if the sleep industry (doctors, pharmaceutical companies, mattress sellers, etc.) is attempting to divert us from our natural patterns. Rather than attempting to shoe-horn sleep into an idealized pattern, individuals should find the regimen that works best for their biology and lifestyle demands.
You might think tribal sleep means everyone sleeps and wakes at the same time, but that isn’t how it plays out in big groups. Depending on the situation, some individuals might be designated look outs or protectors, and even if that is not the case different people will have different daytime experiences, maladies, and sleep patterns. It is a wrong to think that all sleep patterns in the camp are synchronized. But it’s also true that social sleeping individuals influence each other. If a game breaks out, people might choose to get up and participate, waiting to sleep until later.
Nevertheless, sleep can be a social activity, and this is more obvious in primitive living arrangements. The modern pattern of individuals sleeping along or with one (sometimes sexual) partner is rare, historically. Throughout the ages, people have slept with or near their children, parents, siblings, neighbors, and other community members. Infants usually slept with their mothers. In primitive cultures, infants do not sleep alone, according to at least one anthropologist who speculates separation of mother and infant may contribute to the risk of sudden infant death syndrome. When babies started sleeping in separate rooms from their parents, incidence of sudden infant death syndrome rose. When the infant is cradled with the mother, the mother may sleep shallower, but can respond to subtle changes that may indicate breathing problems. Nighttime feedings are also easier this way as the parents do not have to get out of bed.
Rituals and Religious Practices
Sleep is tied up with mysticism, superstition, the divine, and the supernatural. Forced sleep deprivation (and the hallucinations that can result) are sometimes employed in religious ceremonies.
The ancient Egyptians with their death obsession spent a lot of religious energy on sleep, too. The elaborate hairstyles worn by the upper class prompted creation of a headrest for sleeping time to protect the hair and when a teen got a headrest it may have been a symbol of the transition from youth to adulthood. The headrests may have kept bugs off the head, too, as well as allowed cooling in the hot climate. The Egyptians also thought sleep was a time when they could communicate with the dead.
Why did we give up the ancient practices?
Historians Craig Koslofsky and Roger Ekirch point to a decline in bi-phasic sleep starting in Europe in the 1600s. Modern life is about uniphasic sleep (or at least an assumption of it) and much distress over nighttime awakenings may be due to the false notion that healthy sleep should be uninterrupted. Indeed, Ekirch identified hundreds of literary references from before 1900 to a first and second sleep periods An hour or two between the sleep periods was commonly reported, time that could be spent socializing, in prayer, or even in work.
Is sleep maintenance insomnia not a defect, but a description of normal sleep patterns? We are not willing to go that far. In healthy bi-phasic sleep the person does not experience multiple awakenings during the night, and more importantly, does not have daytime sleepiness. So we still say there is sleep maintenance insomnia even if we acknowledge that the ideal of a single block of uniphasic or monophasic sleep is probably a false ideal.
Electrification and the advent of lighting and electronic devices has been implicated in modern society’s sleep problems. But the problem with this artificial light might not be that it mimics the Sun and screws with circadian rhythms as much as it encourages people to work and play over a greater period of the day – starting early and going late – and pushes time for sleep to a smaller window. The person may allow enough time for sleep, but attempt to get it all in one unbroken 8-hour period. Allowing 9 hours with time for nighttime awakenings may be more feasible.