Sleep and growing older
We spend about a third of our lives sleeping, and as we grow older, we start to experience changes in our sleep. This can be when we sleep, the quality of sleep we get and how much sleep we need.
Here, we take a look at sleep and ageing, the relationship between the two and how our bodies adapt to changing sleeping patterns.
How much sleep do we need when we get older?
Sleep is essential for our health, no matter what age we are.  How much sleep you need depends on your age, for example newborn babies need as much as 17 hours sleep a day, whereas someone over the age of 65 needs between 7 and 8 hours of sleep.  Below is an overview of The National Sleep Foundation’s recommendation for nightly sleep determined by your age:
- Birth to 3 months: 14 to 17 hours
- 4 to 11 months: 12 to 15 hours
- 1 to 2 years: 11 to 14 hours
- 3 to 5 years: 10 to 13 hours
- 6 to 13 years: 9 to 11 hours
- 14 to 17 years: 8 to 10 hours
- 18 to 64 years: 7 to 9 hours
- 65 years and older: 7 to 8 hours
So, why does the amount of sleep we need decrease as we get older? When we are young, sleep has important effects on growth, especially in early infancy. Napping plays an important function in the development of young children’s motor skills, memory consolidation and attention.  As we get older, our growth and development slow, and consequently the need for sleep decreases. When we pass the age of 18, and into adulthood, our sleep needs remain consistent.
It is not just how much sleep we need that changes as we grow older; it is also how much deep sleep we get each night. 
How does our sleep patterns change as we age?
As we get older, our sleep patterns change – this is also known as our ‘sleep architecture’ – these changes are thought to contribute to sleep problems. [3,4]
Our sleep follows a pattern between different stages (or states) of sleep; from light sleep, to deep (slow wave) sleep, and into REM sleep (dreaming). [3,4] Each stage has an important function to play in our physical and mental health. REM sleep is important for your memory and cognition; whereas deep sleep is important for storing memories, learning, protecting the health of your heart, energy conservation, the health of your immune system, and repairing damaged tissues or cells within the body. [5,6]
Growing older means less deep sleep and more light sleep. When we are in a light sleep, we are more prone to waking in the middle of the night, resulting in daytime tiredness and exhaustion. [4,7]
Why do our sleep patterns change as we age? Our sleep is controlled by two key systems; homeostasis and our body clock (also known as circadian rhythm) which are influenced by certain hormones in the body, and it is changes in the release of these sleep-related hormones that is evolving our sleep architecture as we age.
How age affects homeostasis, our body clock and sleep -related hormones
Homeostasis controls when we sleep and when we wake – it does this by increasing the pressure to sleep the more we are awake (also known as ‘sleep debt’) and when we sleep this pressure lessens. As we get older the pressure to sleep all the time (like in infancy) reduces resulting in a reduction of Total Sleep Time (TST) which is why adults don’t feel the need to sleep as much as young children.
Our body clock, or circadian rhythm, is another system which influences when and how much we sleep. With normal aging there are changes in the hormones that influence our body clock, these changes include: 
- GROWTH HORMONE – growth hormone and deep sleep influence each other and the reduction in deep sleep with age is associated with a reduction in growth hormone – which rapidly declines after adolescence 
- MELATONIN – the level of melatonin in our body is influenced by exposure to light. If it is dark your body starts to produce melatonin which makes you want to sleep, and when it is light the melatonin levels fall in your body causing you to wake. As we age the secretion of melatonin is affected which is connected to sleep disruption in older adults 
- CORTISOL – Cortisol is a hormone which helps wake us up. The more cortisol in our body the more awake we feel. Deep sleep inhibits the release of cortisol and since older people do not get as much deep sleep as younger people it causes in a higher level of nocturnal cortisol which contributes to frequent night time awakenings and less time sleeping at night.
Sleep timing changes with age
Our body clock usually tells when it is time to sleep and when it is time to wake, but our body clocks may be giving us different times of the day to sleep and wake depending on our age. [4,7]
Newborns will sleep at any time of the day or night depending on the needs of their body. However, by the age of six or seven many children will have stopped napping during the day, since many of them are in school, and will consolidate all their sleeping until night-time.
Did you know that adolescents have a ‘Delayed Sleep-Wake Cycle’ which means they find it difficult to fall asleep too late at night and wake later in the morning? We sometimes call people who experience delayed sleep-wake cycle – night-owls. 
Another interesting change in sleep to affect older adults is an increase in the frequency of daytime naps. Sleep timing in older people differs because they are getting less sleep at night and compensating for the lack of night-time sleeping by napping during the day.  Instead of sleeping later at night like adolescents, older adults seem to go to bed earlier and wake up early – this is called ‘Advanced Sleep-Wake Cycle’ – which can colloquially be known as ‘early birds’. 
Risk factors for sleep disturbances in older adults
Did you know that nearly 7 out of 10 adults experience problems that affect sleep quality? 
As part of normal aging there is an expected reduction in the ability to stay asleep, the length of time sleeping during the night, and the quality of sleep. However, there are other factors that can increase the risk of sleep disturbances in older adults, which include:
- Physical ill health – Chronic conditions like COPD, diabetes, chronic pain, multiple sclerosis, cancer, arthritis, gastro-oesophageal reflux disease (GORD), and nocturia (frequent need to urinate at night) are commonly linked to sleep problems like insomnia. [4,8]
- Substance use or dependence – the consumption of alcohol, caffeine, nicotine, opioids, and drugs have been associated with sleep disturbances. 
- Mental ill health – Depression, anxiety, PTSD, bipolar disorder, and other psychiatric problems are frequently linked to sleep disturbances like insomnia. [4,8]
- Primary sleep disorders – there are several primary sleep disorders that are common in older adults such as insomnia, obstructive sleep apnoea, and restless leg syndrome (RLS).
- Environmental factors – temperature, noise and light exposure are associated with sleep disturbances in older adults. 
- Lifestyle – older adults tend to be more sedentary and have more flexible schedules which offer the opportunity to nap during the day – these factors are thought to affect homeostasis and circadian rhythm which can lead to sleep disturbances. 
- Social life – older adults who are less involved in social activity, or who lose loved ones can experience isolation, loneliness, and emotional distress which can all contribute to sleep disturbances. 
Sleep and aging
Changes in sleep are a normal part of aging and the most common changes associated with getting older are: 
- Sleeping less during the night
- Napping more during the day
- Waking more during the night
- Going to bed and getting up earlier
- Less deep sleep, and more light sleep
Although these changes are part of getting older you can still help yourself get a better night sleep by looking after your physical health, addressing any emotional issues, avoiding substances that affect your sleep, and improving your sleep environment.  There is no one-size-fits-all when it comes to a better night’s sleep, it is all about experimenting and finding what healthy changes help give you a better night’s sleep.
- How much sleep do we really need – Sleep Foundation
- Children and sleep – Sleep Foundation
- Aging and sleep – Sleep Foundation
- Li, Junxin et al. “Sleep in Normal Aging.” Sleep medicine clinics 13,1 (2018): 1-11.
- Zielinski, Mark R et al. “Functions and Mechanisms of Sleep.” AIMS neuroscience 3,1 (2016): 67-104.
- Sleep Physiology – Joshua E. Brinkman; Vamsi Reddy; Sandeep Sharma.
- Changes in Sleep with Age – Harvard Med
- European guideline for the diagnosis and treatment of insomnia 2017
- Sleep Tips for Older Adults – Help Guide