Sleep Needs by Age
How Much Sleep do we Need?
The National Sleep Foundation published a study by 18 sleep scientists and researchers in Sleep Health that shows the number of hours needed by all ages, divided into 9 age divisions. They're listed as ranges because gender has an influence, as well as lifestyle and health.
Newborns and Infants
Newborns don't have an established circadian rhythm; it isn't established they're 2-3 months old. Infants tend to sleep in several phases throughout the day (polyphasic), sleeping from 2.5 to 4 hours at a time. By around 12 months, infants start sleeping more at night. At this point, they start to sleep more like adults in that there are no bodily movements during REM (rapid eye movement) sleep, which is when people dream. Previous to 12 months, babies will move during REM sleep.
Recognizing when school-age children aren't sleeping enough can be difficult as tired kids tend to not slow down, they speed up. They'll engage in behaviors that look like ADHD. This includes resisting going to bed at night, even though they're tired.
Children with ADHD can cause sleep loss in children, as well as other issues such as sleep apnea (when people stop breathing for periods throughout the night). It was previously believed that sleep apnea only occurred in adults, but now the America Academy of Pediatrics recommends ask about and screen for sleep apnea in children.
According to the National Sleep Foundation, circadian rhythms shift after puberty, making teens want to go to bed after 11 pm and wake up later. With teenagers having the earliest start times, they are often getting up at 5 am to be at school by 7 am, which makes it rarer that a teen will get enough sleep. One study found that only 15% of teens reported sleeping 8.5 hours per night.
Because teens are sleep-deprived during the week, they sleep more on the weekend, which can make the problem worse. One of the top recommendations from sleep experts is to fall asleep and wake up at the same time every day.
A problem that many teens share with adults is the use of back-lit devices late at night, which can prevent sleepers from getting quality sleep.
Lack of sleep in teenagers has a long list of drawbacks, including:
- drowsy driving leading to car accidents
- reduced emotional control, leading to more fighting with parents, siblings, and peers
- poor cognitive ability, focus, decision making, and reaction time, leading to poor grades, athletic performance, and choices
- poor impulse control, which can create and strengthen bad habits
- skin issues such as acne
Adults tend to not get enough sleep for a list of reasons:
- stress from job and family
- consuming caffeine too late in the day
- looking at blue-light emitting devices within 90 minutes of going to bed
- inconsistent sleep schedule
- eating too late
- lack of exercise
- issues with the mattress: too hot, too soft or hard, and/or old
Many adults aged 65 and older nap during the day because they don't get enough quality sleep at night. One of the reasons they don't sleep well is because of medical conditions such as restless legs syndrome (RLS). The National Institutes of Health estimate that 10-35% of seniors have RLS, which results in uncomfortable sensations in the legs creating an irresistible urge to move them. Symptoms occur in the evening and often during sleep. Around 80% of people with RLS also have periodic limb movement disorder (PLMD), and one study found that around 45% of all seniors have at least mild PLMD.
Many seniors also suffer from illnesses and take medications, both of which can disturb sleep.
Another common issue among seniors is that it takes them longer to go to sleep, with one study showing 13% of men over 65 and 36% of women taking more than 30 minutes to fall asleep.
According to the National Sleep Foundation, seniors have trouble sleeping for several reasons. One is the change in the phases of sleep, where many seniors spend more time in the lighter phases of sleep and less in the deeper, more restorative phases.
Sleep fragmentation (waking up during the night) is also common, which greatly reduces the ability to wake up well rested.
Women need on average 20 more minutes per night more than men, though some women need more than that. One theory as to why is because women multitask more than men and have busier schedules, which results in their brains using more energy and therefore needing more recuperation. If this theory is correct, then men that have complex jobs that require a lot of decision-making and lateral thinking will need more than the average male as well. Another possible reason is the monthly hormone cycle that occurs with menstruation.
According to the National Institutes of Health, women do sleep more than men. However, there are several things that can make it difficult for women to get enough quality sleep:
- Their male partners' snore (40% of men snore as opposed to 24% of women)
- Stress from family and job responsibilities
Sleep Needs During Pregnancy
Pregnant women need more sleep, especially in their first trimester, which includes more sleepiness during the day. This is due to the rise in progesterone, as well as the metabolic changes the body is going through.
They also are more likely to experience parasomnias, which are unusual behaviors that occur just before falling asleep, during sleep, or when waking up. Common parasomnias for expecting mothers are restless legs syndrome (RLS), snoring, and insomnia.
Expectant mothers in their first trimester will also have more frequent bathroom visits to urinate, due to the uterus pushing on the bladder. Swollen breasts, cramps, and nausea can also make it hard to fall asleep.
In the second trimester, women tend to sleep better, as many of the changes have already occurred in the first trimester. However, it's not uncommon to experience leg cramps (often in the calves) as well as heartburn (due to the uterus pushing on the stomach).
In the third trimester, sleep gets worse again due to (RLS), frequent urination, anxiety about the upcoming delivery, and lower back pain.
After the baby is born, new mothers will often find it easier to sleep because they're sleep deprived. Babies are often awake every hour to few hours, so mothers can't get into the deeper, restful phases of sleep, so when they get a chance to sleep, the brain will try to make up the sleep deficit as quickly as possible.
Breastfeeding is sleep-inducing because the hormone that promotes lactation, prolactin, is a soporific, or sleep-promoting.