Sleep is important for health. We spend around a third of our lives asleep. Sleep deprivation has been linked to a number of health conditions, including obesity. It can also lead to accidents.
Sleeping fewer than 7 hours in every 24 hours is classified as short sleep duration.
In the United States, there is concern that many people are not getting enough sleep. This has been linked to factors such as shift-work, multiple jobs, and spending time watching television and using the Internet.
Fast facts about sleep
How much sleep we need depends on individual requirements, including age.
Sleep affects our performance, mood, and general health.
Sleep deprivation has been linked to long-term adverse effects on health, and a higher risk of premature death.
Most tips for a good night’s sleep are based on good routines.
Many sleep disorders lead to excessive daytime sleepiness, difficulty falling or staying asleep, or abnormal events during sleep.
Sleep in adults
Restful sleep is important for physical and mental wellbeing.
The following amounts of sleep are recommended in every 24 hours, depending on the age group:
From 18 to 60 years: 7 hours or more
From 61 to 64 years: 7 to 9 hours
From 65 years: 7-8 hours
However, the amount of sleep a person needs will depend on how they feel and their productivity.
Feeling sleepy or depending on caffeine during the day, for example, may signal insufficient or poor quality sleep.
As we grow older, the structure of the sleep pattern, called “sleep architecture,” changes considerably.
These changes affect:
how we fall asleep and stay asleep
how much time we spend in each stage of sleep
how well we start sleeping and stay asleep
The overall amount of sleep and sleep efficiency both tend to decline with age. As we age, we tend to wake earlier and go to bed earlier.
People aged 65 to 75 years, for example, typically wake up 1.33 hours earlier and go to bed 1.07 hours earlier than those aged 20 to 30 years.
Decreases in melatonin synthesis in older adults have been linked to sleep disorders and a range of adverse health conditions.
Melatonin is the neurohormone produced in response to diminishing light levels at dusk. Levels drop in the early morning before we wake.
Shift work, overseas travel, aging, and other facts can affect melatonin synthesis. This can then disrupt sleep patterns and sleep quality.
Sleep in children
The Centers for Disease Control and Prevention (CDC) suggest that infants, children, and teenagers need the following sleep in every 24 hours:
Up to 3 months of age: 14 to 17 hours
From 4 to 12 months: 12 to 16 hours
From 1 to 2 years: 11 to 14 hours
From 3 to 5 years: 10 to 13 hours
From 6 to 12 years: 9 to 12 hours
From 13 to 18 years: 8 to 10 hours
Newborns do not have an established circadian rhythm. The circadian rhythm and need to sleep more during the night rather than the day as part of a 24-hour cycle develop from the age of 2 or 3 months.
Young infants do not have long, continuous episodes of sleep. Instead, they sleep for 16 to 18 hours a day for short periods of between 2.5 and 4 hours.
By the age of 12 months, sleep patterns develop that involve less sleep and is concentrated more around the nighttime.
The infant also loses a feature of infant sleep known as active sleep, in which there is a lot of body movement. Instead, muscle paralysis with atonia takes place during REM sleep.
Physiological needs, cultural environment, and social changes, such as reduced daytime napping and school routines, mean that the amount of sleep children get progressively decreases into adolescence.
Research about alertness, sleep-wake cycles, hormones, and circadian rhythms indicates that adolescents, as determined by puberty rather than only age in years, need up to 10 hours of sleep every night.
However, over two thirds of high school students say they get less than 8 hours on school nights.
A lack of sleep can be dangerous for those who have to drive.
Studies of the effects of sleep deprivation show that a lack of sleep can affect our:
Sleep contributes to the proper functioning of the nervous system, including cognitive abilities and emotional health.
Sleep deprivation can decrease alertness and reduce response times. One way to think about this would be the feeling of being drunk, when your ability to drive or operate heavy machinery would be altered, which occurs after not having any sleep for 24 hours straight.
Brain imaging has shown that pathways for memory and learning are active during certain sleep stages. We need sleep for clear thinking, normal reactions and the creation of memories.
Emotional and social functioning may depend on good sleep, and mood is affected by deprivation. Not sleeping enough may increase the risk of depression.
Sleep enables the body to produce hormones essential to childhood growth and development and health maintenance in adults.
These hormones help the body to:
High blood pressure, heart disease, and other adverse medical conditions may be more likely if sleep is poor in quantity or quality.
Sleep also appears to promote metabolism and energy use. Poor sleep has been linked to weight gain, obesity, diabetes mellitus, and poorer dietary choices.