If you're a parent who thinks that dragging your teenager out of bed at 8:30 on a Saturday morning is good for them, think again. Research shows that our biological clock shifts throughout life, resulting in different sleep patterns at different stages of life. Due to forces beyond their control, teenagers aren't usually ready for bed until the wee hours of the morning, which means they need to sleep in the next day to get the rest they need.
It turns out babies, teenagers, adults and older adults each have their own ideal sleep schedule, not all of which fit the clock the world runs by. Below, Sonia Ancoli-Israel, PhD, a professor of psychiatry at the University of California San Diego School of Medicine, discusses how our sleep patterns evolve over time, and what you can do to sleep better.
What is the common sleep pattern for infants?
Infants have a sleep pattern that's very unique to them and the stages of sleep are different than what we see in adults. They need to sleep about 10 to 12 hours throughout the 24 hours. Most infants nap around four or five times throughout the day, and their sleep is disrupted at night because they need to get up, primarily to eat.
As they grow into little boys and girls, the sleep pattern changes. The number of naps will decrease throughout those early years. By around age 3, children will be taking maybe only two naps. By age 5, they've stopped their napping. But they still need about 10 hours of sleep at night.
What is the natural sleeping pattern for teenagers?
Adolescents still need about 10 hours of sleep at night. I don't know too many teenagers who get that amount of sleep, but that's what they need to feel refreshed and to be able to really function and be alert throughout the day.
The other thing that happens to adolescents is that the timing of their sleep changes. Their circadian rhythms, or the biological clock, shifts. While most children go to bed around 9 pm at night, teenagers don't get sleepy until maybe 1 to 2 in the morning. They still need their 10 or 11 hours of sleep, which now means they're not going to wake up until maybe 10 or 11 in the morning.
Most parents think, "My child is being lazy." But in fact, it's a very normal pattern for adolescents to experience. We call this a delayed sleep phase because their whole pattern is delayed when compared to the clock we live by.
This sleep pattern can be a real problem for adolescents in terms of getting to school on time or even being alert enough for early morning classes because their bodies and brains aren't quite awake yet. There is actually a movement around the world to start high schools a little later in the morning, specifically because of this problem.
What does the sleep pattern look like in most adults?
As adolescents continue to grow into adulthood, the pattern shifts back, so that most adults get sleepy around 11 pm. They'll sleep about 8 hours because now we need less sleep as we get into adulthood, which means that they're waking up around 6 or 7 in the morning.
There are individual differences in how much sleep adults need, and people need to figure that out for themselves. The way you do that is by finding out how much sleep it takes for you to feel fully alert during the day. And what fully alert means is that you're able to stay awake until it's time to go to bed at night.
Do we need less sleep as we get older?
There is this myth that as we get older, we need less sleep. The truth is that our ability to sleep changes as we get older, but the need for sleep probably doesn't. As we get older, the amount of deep sleep that we have decreases. It actually starts decreasing at around age 20. As we get older, our sleep architecture changes. We begin losing some of our deep sleep and the less deep sleep you have, the more time you'll spend in lighter stages of sleep. If you're spending more time in lighter stages, that means that you're more likely to react to noises or things in the environment that will wake you up.
What kind of sleep patterns do older adults have?
Older adults get sleepy early in the evening, perhaps six, seven, eight o'clock at night. If they went to bed at that hour, they'd still sleep about seven, eight hours. But that means that they're now waking up at three, four, five in the morning. And, of course, the biggest complaint that older adults have is "I'm waking up in the middle of the night."
The problem is that although older adults are getting sleepy early in the evening, most of them are not going to sleep. They're still staying up until about 10 or 11, but their body is still going to wake them up at four or five in the morning. Now they're not getting a full night's sleep. So they might be tired during the day. They'll take an afternoon nap. That afternoon nap allows them to stay alert later into the evening, but they're still going to wake up at 5 in the morning because of their biological clock.
Another problem occurs when many older adults sit down to read or watch television in the evening. Because their body is ready to go to bed at that hour, they'll fall asleep. They'll sleep for an hour, maybe two, in front of the TV. When they wake up and get into bed, suddenly they can't fall asleep. So they'll have difficulty falling asleep and their body will still wake them up at 4 in the morning.
So now they get into this pattern of difficulty falling asleep, difficulty staying asleep. They'll come in and tell their doctor, "I have terrible insomnia," when, in fact, it might all be because of this advanced sleep phase, meaning one gets tired earlier in the day.
What can older adults do to sleep through the night?
The best way to shift your biological clock, so that you can stay alert later into the evening and sleep later in the morning is with bright light. Bright light is one of the strongest cues that our body has for knowing when to go to bed and when to get up.
Older adults experiencing this advanced sleep phase should spend time outdoors as late in the day as possible while the sun is still out. So go for an afternoon walk, do your gardening in the late afternoon, but get that late afternoon, early evening light exposure. At the same time, avoid morning light. So if you go for an early morning walk, wear dark sunglasses because the mechanism is primarily through our eyes.
Taking a short nap early in the afternoon is not a bad thing for older adults. But the longer your nap and the later in the day your nap is, the more likely it is to disrupt sleep later on at night.
What kind of sleep disorders can affect adults?
There are a lot of different sleep disorders. These would include insomnia, which means difficulty falling or staying asleep. Insomnia can be caused by lots of other things, so insomnia might be the main problem, or it might be secondary. It might happen because of stress, medical illness or medications. It could happen because your biological clock is shifting so that you get tired earlier.
Other common sleep disorders include sleep apnea, which is a disorder marked by loud snoring where obstructed airflow leads disturbs sleep. Periodic limb movements in sleep is another disorder, where people kick or jerk their legs every 20 to 40 seconds for periods throughout the night. Both of these disorders are more common among the elderly.
How can we address sleep problems?
In treating all these sleep disorders, particularly the insomnias, the first thing that you have to learn is good sleep hygiene, or good sleep habits. That would include trying to go to bed and get out of bed at the same time every day, not napping too long in the afternoon, avoiding alcohol in the evening because although alcohol may make you sleepy initially, it wakes you up later on in the night.
Exercising during the day is helpful, so you double up on both getting your bright light exposure and getting your exercise. Use the bedroom only for relaxing events. So don't watch the news or read a murder mystery in bed. If you wake up, avoid looking at the clock because you have to open your eyes, turn your head, maybe even lift the clock. The best thing to do is turn that clock around so you're not tempted to look at it.
When should someone consult a doctor about sleep problems?
When your sleep starts interfering with your daytime functioning, that's the time to go see your health care professional about it. When you're too tired to do the things that you want to do during the day, when you find yourself having a hard time staying awake, when you're not thinking as clearly—those are all symptoms of poor sleep at night. That's when it's important to see your physician to get your sleep fixed, so that you can function optimally during the day.