It happens almost without us noticing. At first, we simply start getting tired a little earlier. Then, the hour when we once would have been heading out for the evening becomes the hour when we struggle to stay awake until the end of a movie. And in the morning, even without an alarm clock, we wake up at exactly the same time, day after day.We used to laugh at our parents for falling asleep in front of the television and waking up before everyone else. Now we’re discovering that the joke is on us. As we age, our sleep schedule shifts earlier, whether we want it to or not. Why does this happen?Have we become our parents? Waking up early (Photo: shutterstock)”It’s true, but only partially. In other words, it doesn’t apply to everyone,” says Dr. Amit Green, a psychologist specializing in sleep at Assuta Medical Centers, when asked about the tendency to wake up earlier with age. “A large proportion of older adults tend to go to bed earlier and wake up earlier.”This is not the first change our sleep undergoes.”In infants, we see polyphasic sleep, with cycles of two or three hours. A baby sleeps between 14 and 17 hours a day,” Green says. “Later, we begin to see a longer period of nighttime sleep along with several daytime naps. Toddlers already have a longer stretch of nighttime sleep and one daytime nap, with total sleep declining to about 12 to 13 hours. As children grow older, they stop taking daytime naps and sleep about 10 to 11 hours, mostly at night.”Then comes adolescence, when parents trying to get their children to bed discover that their biological clocks run on a different schedule.”As children enter adolescence, we see a delay in the biological clock,” Green explains. “Teenagers push back both their bedtime and their waking time. Sleep is a behavior that develops and is influenced by the stage of life we’re in.”But what drives all these changes?Two main forces help determine when we sleep: sleep pressure, which builds the longer we remain awake, and the biological clock, which regulates our periods of wakefulness and sleep. The clock adjusts in response to environmental signals, particularly light. Meal times, physical activity and social interactions also help signal where we are in the daily cycle.”Exposure to daylight is the mechanism that synchronizes the sleep-wake cycle,” Green says. “When there is light, it enters through the eyes and the information reaches the biological clock in the brain. The clock signals the pineal gland to stop secreting melatonin, the sleep hormone, and the body shifts into a state of alertness and activity. This is also connected to attention and concentration. When the sun sets and darkness falls, the clock signals the body to begin secreting melatonin, and about two or three hours later, we enter the sleep phase.”Dr. Amit GreenPhoto: Yossi Zwecker, Assuta Sleep Institute But among the many changes the body undergoes as it ages, the process of secreting this hormone also changes.”We know that melatonin secretion becomes less effective, with declines in both the quantity and quality of secretion. This also interferes with the biological clock and the sleep-wake cycle,” he says.The extent of these changes varies from person to person, and melatonin alone does not explain why any particular individual wakes up early.How complicated is the picture? A 1998 study published in the American Journal of Physiology examined 44 older adults and 101 younger men. The older participants did indeed wake up earlier, and their biological rhythms were also shifted earlier. But that shift alone did not explain their waking times. The researchers also identified changes in the relationship between the internal clock and the time of awakening.Children sleep for about 10 to 11 hours a night (Photo: shutterstock)Green points to another factor: the lens of the eye.”We also need to talk about how light is received,” he says. “We know that in older adults, the lens of the eye becomes cloudy. Some undergo eye surgery to correct that cloudiness. Vision deteriorates, and less light passes through the lens. That can also interfere with the biological clock.”Such clouding occurs, among other conditions, with cataracts. Dr. Sairam Parthasarathy, director of the Center for Sleep and Circadian Sciences at the University of Arizona, also discussed the possible link between the amount of light reaching the eyes and sleep timing in an interview with HuffPost.”Exposure to daylight is the mechanism that synchronizes the sleep-wake cycle. When there is light, it enters through the eyes and the information reaches the biological clock in the brain. The clock signals the pineal gland to stop secreting melatonin, and the body shifts into a state of alertness and activity. When the sun sets and darkness falls, the clock signals the body to begin secreting melatonin, and about two or three hours later, we enter the sleep phase.”But physiological changes explain only part of the picture.There is something else the biological clock grows accustomed to over decades of working life: leaving home in the morning, being exposed to daylight and activity, then returning home in the evening. Sometimes, after retirement, that distinction becomes blurred.”When people retire, they work less, go outside less and sometimes become less mobile,” Green says. “They spend more time in environments where the distinction between daytime and evening is no longer as pronounced as it once was, with constant, dim lighting. On the one hand, they don’t get enough daylight, and on the other, they may be exposed to too much artificial light in the evening. This can disrupt the biological clock.”Changes in daily routines therefore compound the physiological changes taking place in the body.”Some people start taking afternoon naps that weren’t possible when they were working,” he continues. “Now they can sleep for an hour or two in the afternoon. This allows them to stay alert longer in the afternoon and evening, go to bed later and also wake up later.”When there is no longer a need to get up for work or care for children in the morning, waking times can also change.”They have the option of going to bed later and waking up later. That happens too, and it’s important to point it out.”A large proportion of older adults tend to go to bed early and wake up early (Photo: shutterstock)But as we age, it is not only the times we fall asleep and wake up that change. Sometimes, the quality of sleep itself changes as well.A meta-analysis published in the journal Sleep in 2004 combined 65 studies involving 3,577 participants ages 5 to 102. Across adulthood, increasing age was associated with less deep sleep, more time spent awake during the night and declines in both sleep duration and sleep efficiency — the proportion of time spent in bed that is actually spent sleeping.After age 60, only the decline in sleep efficiency remained statistically significant in the analysis. The associations also varied according to participants’ medical conditions, medications and sleep disorders.Does this mean we need fewer hours of sleep?”We have to be careful about making that kind of blanket statement,” Green says. “Broadly speaking, we see a downward trend in sleep duration over the course of life. For adults, we’re talking about a range of seven to nine hours, while for older people, we can talk about a range of six to seven hours.”These are sleep durations observed in some people, but the amount of sleep someone actually gets is not necessarily the amount their body needs. According to the U.S. National Institute on Aging, older adults are also generally advised to get seven to nine hours of sleep a night.The biological clock synchronizes with our habits, which can change after retirement (Photo: shutterstock)And some people do not fit neatly into these ranges.”Some people naturally need less sleep and can get by on five, five and a half or six hours while still feeling good and functioning well,” Green says. “I often meet people in the clinic who tell me, ‘I sleep five and a half hours, feel good, function well and wake up refreshed.’ They hear that they’re supposed to sleep six, seven or eight hours, and they feel frustrated because they aren’t reaching that number. But if they feel good and function well, that’s fine.”According to Green, the opposite can also be true.”Some people need eight hours of sleep or even more. If they sleep less than that, they feel tired and sleepy. Sleep varies greatly from person to person.”Someone who falls asleep at 9 p.m. and wakes up refreshed at 5 a.m. and someone who falls asleep at midnight and wakes up exhausted at 5 a.m. may find themselves in the kitchen at the same hour. But for Green, the crucial questions are what happened during the night and how they feel in the morning.”If you have trouble falling asleep, if you wake up during the night and struggle to get back to sleep, if the experience of sleeping becomes frustrating and unpleasant, and you wake up in the morning tired and sleepy rather than refreshed, it’s time to start investigating.””If you have trouble falling asleep, if you wake up during the night and struggle to get back to sleep, if the experience of sleeping becomes frustrating and unpleasant, and you wake up in the morning tired and sleepy rather than refreshed, it’s time to start investigating,” he says.Even someone who sleeps six or six and a half hours but wakes up feeling unrefreshed may need an evaluation, particularly if they had difficulty falling asleep or experienced repeated awakenings.Pain, medications, psychological factors and sleep apnea are among the possible causes that should be considered.For those looking to reduce early awakenings, Green offers several practical tips.”It’s important to make sure you get up at a consistent time in the morning,” he says. “Establish a morning routine: take a shower, do 15 minutes of physical activity and get at least 30 to 60 minutes of daylight exposure.”In the evening, he recommends “going to bed when you feel tired and sleepy.”If you wake up in the middle of the night, try to calm your body and mind and return to sleep (Photo: shutterstock)And if you wake up in the middle of the night, he suggests not becoming alarmed simply because you’ve awakened.”Tell yourself, ‘I woke up, and that’s OK. I’ll fall back asleep soon. How nice, I still have more time to sleep.'”The idea, he explains, is “to calm yourself down and give yourself a chance to fall back asleep until morning.”Next Saturday, if you wake up before everyone else, you might decide to get up, make some coffee and enjoy the peace and quiet.But if you’re lying in bed exhausted, wishing you could get another two hours of sleep but unable to, it may be worth finding out what’s disrupting your sleep.
