Some people may not consider sleep to be as important to our wellbeing as drinking enough water, getting enough exercise, and eating the right food.  But getting the right amount of high-quality sleep is vital. In fact, getting too little sleep regularly can lead to serious health problems. 

So, how much sleep do you really need every day? In this article, we’ll look at sleep requirements at different ages, why rapid eye movement (REM) sleep and deep sleep are important, health problems associated with lack of sleep, and what you can do to improve your sleep patterns. 

Sleep requirements by age and stage 

The amount of sleep you need changes throughout your life. Infants and young children need a lot of sleep to support their neurological and physical development, while adults tend to need slightly less. Of course, this varies by person and lifestyle – adults may need more sleep at stressful or busy times, or while recovering from an illness or injury. 

Recommended hours of sleep by age^1,2 

Why quality matters just as much as quantity when it comes to sleep

Typically, humans will cycle through four stages during sleep – with different brain activity characterizing each stage. There is one rapid eye movement (REM) sleep stage and three non-rapid eye movement (NREM) stages.  Each cycle lasts around 90 minutes, although earlier cycles may be shorter and later ones slightly longer. Most adults will go through four to six rounds of the sleep cycle during a typical night.³ If your sleep is regularly interrupted or your body is unable to complete the sleep cycle, you may not be getting enough restorative rest – even if you’re technically sleeping for the recommended hours. REM sleep and deep sleep are particularly important.⁴

REM

REM, sometimes called dream sleep, was officially discovered in 1953.⁵ This stage is characterized by rapid eye movement under the eyelids. During REM, the body enters a temporary paralysis (atonia) while the brain works to repair and protect itself, processing and consolidating memories – particularly emotional memory.⁶ Adults spend roughly a quarter of their sleep time in REM sleep. During this stage, brain activity is closest to waking levels, and you experience the most vivid dreams. Dreams can happen during NREM sleep but tend to be less intense.⁷

Deep Sleep 

NREM stage three, also known as deep sleep, delta sleep, or slow-wave sleep, is characterized by the slow pattern of delta brainwaves seen on an electrogram (the output from electroencephalography, EEG). Deep sleep lasts for around 20 to 40 minutes when you first go to sleep, and gets shorter as the night goes on, giving way to more REM sleep. Deep sleep lets the brain reorganize and recharge, helping you wake feeling bright and refreshed. This stage also helps strengthen and support your immune system – that’s why you can feel sick and run down if you’re regularly missing out on sleep.⁸

The impact of low-quality sleep 

We all have periods of low-quality sleep. Parents tend to experience months of sleep deprivation when their children are young. Others may miss out on vital stages of sleep due to stress, depression, or other health issues such as sleep apnea.⁹ Also known as sleep deficiency, low-quality sleep is a concern even when the duration of sleep seems adequate.⁹

Sleep deprivation – including low-quality and inadequate duration of sleep impacts everything from appetite to memory, to aging and mental health. Studies have found that decreased quality sleep can disrupt muscle growth and healing, appetite control, memory, and immune function. Lack of deep sleep is associated with faster aging, alcohol misuse, epilepsy, and depression.^8,10,11 Lack of REM sleep, or restlessness during the REM phase, can also be damaging, contributing to disorders including anxiety, erratic mood, low concentration, and even mild hallucinations in some cases.⁵ In fact, even if overall sleep is adequate in length, lack of REM sleep has similar effects to typical sleep deprivation.¹²

Signs of serious sleep deprivation 

Sleep deprivation seems as if it should be easy to spot – but that’s not always the case. Because lack of quality sleep can be an issue, some people struggle with the symptoms of sleep deprivation without appreciating the duration of sleep is not always the key factor. If you wake up feeling tired or feel tired most of the time despite sleeping the recommended hours, lack of quality sleep could be the issue. If your partner is frequently restless or wakeful during the night, it can impact the quality of your sleep as well.¹¹

Sleep deprivation is associated to several existing health issues.³

• Obesity in adults and children.
• Diabetes and impaired glucose tolerance.
• Cardiovascular disease and hypertension. 
• Anxiety symptoms. 
• Depressed mood.
• Alcohol use.

Is sleep apnea impacting your sleep quality? 

It’s not always easy to pinpoint a cause for sleep deprivation or ongoing fatigue. Sometimes, it comes down to lifestyle or life stage, which means solving the problem requires changing your sleep habits. Going to sleep at the same time each night, avoiding caffeine late in the day, eliminating screen use near bedtime – these can all help you reduce sleep issues and improve sleep quality.¹³ 

However, sleep deprivation can sometimes be caused by another health problem – sleep apnea.  This disorder is one of the most common causes of sleep deprivation, making it a major contributor to a range of health issues in turn.¹⁴ The condition, the most common form being obstructive sleep apnea (OSA), causes breathing to pause repeatedly during sleep, leading to a drop in blood oxygen saturation and restless sleep. Some people with sleep apnea have these short pauses hundreds of times every night, making it very difficult to get enough high-quality sleep.³

Do you suspect sleep apnea may be affecting your sleep? If so, take Fisher & Paykel Healthcare’s sleep apnea assessment. If the results point to sleep apnea, you may wish to consider scheduling a sleep study with your doctor – they’ll be able to offer clarity and come up with possible solutions.  

Frequently asked questions

Why is getting good sleep so important?

High-quality sleep helps the brain reorganize, recharge, and rid itself of toxic by-products that build up during the day. It’s also vital for immunity and memory storage.¹⁵

Why am I still tired after sleeping for eight hours or more?

This could be a sign of sleep deficiency (poor sleep) caused by sleep apnea, stress, or several other chronic health issues such as depression, cancer, Alzheimer’s disease, heart disease, kidney disease, high blood pressure or the aftereffects of stroke.³

Is it possible to sleep too much?

There is a lack of evidence whether sleeping for more than nine hours a night is associated with any health risks.¹⁶ However, it is likely that some health issues cause people to sleep more. If you’re regularly sleeping for 9+ hours and still feel tired, it may be a sign that your sleep quality is lacking.¹⁶

Can napping help me get enough sleep?

Napping can be a way to catch up on temporary sleep debt caused by caring for a sleepless infant, shift work, or other lifestyle factors. However, frequent naps can interfere with your regular sleep and make it more difficult to get enough sleep at night, making sleep issues worse in the long term.¹⁷

What can I do to get more quality sleep? 

People struggle to sleep for all sorts of reasons. If you’re finding it hard to get the recommended seven hours’ sleep each night, start by working on your sleep hygiene – that is, creating a routine to help you develop good sleep habits and eliminating factors that can impact sleep. 

This can include:¹⁸ 

• Going to bed at the same time each night.
• Eliminating caffeine.
• Turning off electronic devices before bed – blue light can inhibit sleep. 
• Creating a calm, dark, and comfortable sleep environment. 
• Exercising regularly. 
• Meditating or journaling to reduce stress before bed. 
• Avoiding naps during the day. 

For more information, go to What are the stages of sleep?

The content is for educational purposes only. It should not be used as a substitute for the medical advice of one’s healthcare provider.