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What is a Sleep Disorder?

Sleep is integral to your physical and mental health. However, multiple studies and surveys have found that many people (ranging from 20% to 50%) in the UK don’t get enough sleep. It is difficult to quantify exactly how many people in the UK experience a sleep disorder, as many people never seek an official diagnosis and instead try to treat their condition themselves. However, the NHS estimates that one-third of people will experience episodes of insomnia at some point in their lives. 

Today, we are going to look at sleep disorders in more detail, including the different types of sleep disorders, the common causes and symptoms and the possible treatment options.

What is a Sleep Disorder?

Sleep disorders affect the amount of sleep you get and the quality of your sleep. A sleep disorder can significantly affect your capability to get the rest your body and brain need to function correctly and significantly impact your abilities, your daily functioning, your overall health, your relationships and your quality of life. 

There are many different types of sleep disorders that have different characteristics and symptoms. Sleep disorders can affect:

  • The quality of your sleep.
  • How much sleep you get per night.
  • Your wakefulness – how many times you wake up and the duration of each waking episode.
  • How long it takes you to fall asleep.
  • Your circadian rhythm.

Sleep is critical to your physical and mental health. Disordered sleep can result in cognitive impairment, a decline in your mental and physical health, decreased brain function and impaired daily functioning. The amount of sleep you need per night can vary from person to person. However, you will need to complete several cycles per night of both rapid eye movement (REM) and non-rapid eye movement (non-REM). 

Sleep disorders can occur on their own or coexist with other conditions. Some people may also experience more than one sleep disorder at a time.

Someone Suffering from a Sleep Disorder

What Causes a Sleep Disorder?

Because there are multiple different types of sleep disorders, there are also many possible causes. Sleep disorders are highly individualised and what causes one person to experience disordered sleep can be different to what causes another person’s sleep disorder.

Some of the most common causes of disordered sleep are listed below.

Mental health conditions

There is a significant relationship between mental health and disordered sleep. Multiple mental health conditions can significantly affect your sleep. Similarly, disordered sleep can also affect your mental health. As well as short-term changes to your mood or mental health, such as heightened stress or acute periods of depression, long-term mental health conditions, such as the ones listed below, can also cause you to develop a sleep disorder:

  • Schizophrenia.
  • Anxiety.
  • Depression.
  • Bipolar disorder.
  • Long-term stress.
  • Post-traumatic stress disorder (PTSD).
  • Alcohol dependency.
  • Addiction to drugs.
  • Mood disorders.

Health conditions

As well as the mental health conditions listed above, there are other health conditions that can significantly affect your sleep, including:

  • Alzheimer’s disease.
  • Parkinson’s disease.
  • Attention deficit hyperactivity disorder (ADHD).
  • Chronic obstructive pulmonary disease (COPD).
  • Overactive thyroid.

There are multiple ways in which menopause can negatively impact your sleep and result in you developing a sleep disorder. Symptoms of menopause, including hot flashes, night sweats and mood changes, can all contribute to disordered sleep. Additionally, because some people going through menopause also develop mental health conditions, such as depression, this can exacerbate sleeping difficulties and result in the development of a sleep disorder. Sleep disorders can occur pre-menopause, during menopause and post-menopause.


Sleep disorders can occur as a side effect of some types of medication. This includes medication that is used to treat conditions such as depression, high blood pressure, Parkinson’s disease, asthma, allergies and some pain medication.

Lifestyle factors

Multiple lifestyle factors can cause or contribute to a sleep disorder, including:

  • High stress levels.
  • High caffeine intake.
  • Drinking excessive alcohol (particularly on a regular basis).
  • Smoking.
  • Taking recreational drugs.
  • Excess exposure to blue light (e.g. from a mobile phone).
  • Poor sleep hygiene or a bad sleep environment.

How Can Problems With Sleep Affect You?

Sleep disorders can have a profound impact on many areas of your life, particularly if you have a chronic sleep disorder (that lasts longer than a few months). Sleep allows your body and brain to perform a number of important functions, including supporting healthy brain function, removing toxins from your brain, promoting memory consolidation, supporting growth and development (in children and young people), regulating hormones and helping to support your immune system.

The amount of sleep you need depends on your age and can vary from person to person. On average, infants and toddlers need 12-17 hours of sleep per night, children need 9-13 hours of sleep and adults need 7-9 hours of sleep. If a sleep disorder prevents you from getting enough sleep, or if the quality of your sleep is poor, you may experience adverse effects in multiple areas of your life. 

Some of the ways poor sleep can impact your life include:

Mental Health

Poor sleep can have a significant impact on your mental and emotional health. Chronic poor sleep can affect your emotion regulation and cognitive function and have a detrimental effect on your overall mental health.

Some ways sleep disorders can affect your mental health include:

  • Increased stress and anxiety.
  • Increased risk of developing depression or the exacerbation of depression symptoms.
  • Difficulties concentrating.
  • Increased emotional reactivity and difficulties with emotion regulation.
  • Feeling irritable.
  • Having low energy and low mood.
  • Increased feelings of loneliness or isolation.
  • Impairments in short-term and long-term memory.
  • Impairments in judgement and decision-making.
  • Impaired daily functioning.
  • Increased risk of mental health conditions, including schizophrenia and bipolar disorder.
  • More likely to experience psychotic episodes, including mania, psychosis or paranoia.
  • Increased risk of suicide.

Physical Health

Sleeping disorders have been linked to a wide range of physical health conditions. Consistently poor sleep can increase the risk of chronic health conditions and can even shorten your life expectancy.

Some of the potential physical health consequences of sleeping disorders are:

  • A weakened immune system.
  • Increased risk of weight gain and obesity (because of a disruption to the hormones that regulate hunger and satiety).
  • Increased risk of Type 2 diabetes.
  • Increased risk of high blood pressure.
  • Increased risk of cardiovascular disease or other cardiovascular issues.
  • Increased risk of stroke.
  • Increased inflammation in the body (which can result in a number of health conditions).
  • Lower pain threshold.
  • Digestive and gastronomic issues, including irritable bowel syndrome (IBS).
  • Reduced libido.
  • Increased sensitivity to pain.
  • Impaired physical functioning (e.g. slower reaction times, a decline in coordination).

Consistently poor sleep can also impact your educational or work performance. You may experience:

  • Concentration difficulties.
  • Memory impairments.
  • Mood disturbances.
  • Decreased productivity.
  • Difficulties making decisions, including making hasty decisions or making decisions you wouldn’t usually make.
  • Difficulties with problem-solving.
  • Difficulties driving or operating machinery safely.
  • Increased risk of accidents in the workplace.

As well as the potential impact on your mental, physical and emotional health, sleep disorder can also affect your life in other ways. Having a sleep disorder can also impact your relationships, particularly if your disturbed sleep also affects your partner or if you experience irritability or low mood. Social withdrawal is also a common characteristic of sleep disorders, most likely because sleep disturbances are commonly related to daytime fatigue.

Sleep Disorder

What are the Types of Sleep Disorder?

There are more than 80 different sleep disorders that you can be diagnosed with. These sleep disorders are categorised into different types, depending on the associated symptoms, the pathophysiology (how they typically affect people) and the affected body system. 

The different types of sleep disorders are listed below:


This is the most well-known type of sleep disorder and is characterised by difficulties falling asleep, difficulties staying asleep and difficulties getting good quality sleep. There are multiple different types of insomnia:

  • Initial (sleep onset) insomnia: This involves difficulties falling asleep – it is the onset of sleep that is affected.
  • Sleep maintenance insomnia: Also known as middle insomnia, this is the most common type of insomnia. People with this type of insomnia struggle to stay asleep and often wake up during the night. They may also find it difficult to fall back to sleep once they are awake.
  • Early waking insomnia: People with this type of insomnia wake up much earlier than they want or need to and usually cannot go back to sleep.
  • Mixed insomnia: Mixed insomnia occurs when people struggle with both sleep onset and sleep maintenance. They may find it difficult to fall asleep and to stay asleep.
  • Paradoxical insomnia: People with this type of insomnia underestimate the amount of sleep they get. They may believe they are sleep-deprived when, in reality, they have a normal sleep cycle.

Sleep-Related Breathing Disorders

This type of sleep disorder is characterised by abnormal respiration and breathing-related disturbances during sleep. It can include gasping for air, choking, grunting or snoring during sleep. Some common examples are:

  • Obstructive sleep apnoea (OSA): This is the most common breathing-related sleep disorder and is characterised by lapses in breathing caused by airways that collapse repeatedly during sleep. This can affect your sleep and your oxygen levels.
  • Central sleep apnoea: This occurs when your brain does not properly transmit signals to your respiratory muscles, or your respiratory muscles do not activate in response to signals. This can result in pauses in respiration.
  • Sleep-related hypoventilation: A lack of air circulating in the lungs can result in elevated carbon dioxide levels in the blood and difficulties breathing.
  • Sleep-related hypoxemia disorder: This occurs when the oxygen concentration levels in your blood drop.
  • Snoring: Many people don’t realise that snoring is a sleep disorder. If you snore multiple times per week on a long-term basis, it is classed as a sleep disorder.
  • Catathrenia: Also called nocturnal groaning, this disorder is characterised by repeated episodes of groaning or moaning during sleep.

Sleep-Related Movement Disorders

Someone with a sleep-related movement disorder will experience increased movement before or during sleep. They will experience repetitive movements, such as jerking or twitching, that interfere with their sleep. Some common examples are:

  • Restless legs syndrome (RLS): This involves a strong and overwhelming urge to move your limbs, particularly when you are sedentary. These urges can be uncomfortable, annoying or painful and can be relieved when you move the affected limb.
  • Periodic limb movement disorder (PLMD): This involves repetitive movements, such as twitching, jerking or kicking of your arms, legs or feet. This can occur multiple times per hour for up to 90 seconds per episode.
  • Sleep bruxism: This involves involuntary teeth grinding and teeth clenching during sleep.
  • Sleep-related rhythmic movement disorder (SRMD): This involves repetitive, rhythmic movements that occur when you are asleep or as you are falling asleep. It can manifest in different ways, including moving your limbs, your entire body or your head (e.g. banging your head). You may also hum or make other sounds while you are moving.

Central Disorders of Hypersomnolence

This category of sleep disorders includes daytime sleepiness that occurs in the absence of other sleep disorders. An individual with this type of sleep disorder may experience an overwhelming need to sleep.

The most common central disorders of hypersomnolence are:

  • Narcolepsy: This involves difficulties regulating your sleeping and waking patterns and can include sleep attacks – where you fall asleep suddenly, without any prior warning. It also involves excessive sleepiness during the day, sleep paralysis and cataplexy – a temporary loss of muscle control.
  • Idiopathic hypersomnia: This shares many of the same symptoms as narcolepsy. People with this condition will sleep for long durations but wake up feeling groggy and unrested. They may also experience sleep inertia and excessive sleepiness during the day.
  • Kleine-Levin syndrome: This disorder is characterised by hypersomnolence (needing excessive amounts of sleep), excessive eating and behavioural abnormalities.

Circadian Rhythm Sleep-Wake Disorders

This category of sleep disorders is characterised by disruptions in the timing of sleep. Someone with a circadian rhythm disorder may have difficulties falling asleep and staying asleep. Some common examples are:

  • Delayed sleep phase disorder: This involves an unusual sleep-wake cycle whereby you will be unable to sleep until much later than is considered normal but will also not wake up until much later than is considered normal. For example, a person with this disorder may go to sleep at 3 am and wake up at 1 pm every day. You will be most alert and productive at night and struggle to function normally in the morning.
  • Advanced sleep phase disorder: This disorder is the opposite of delayed sleep phase disorder. It is characterised by sleeping early in the evening and waking early in the morning (before dawn). For example, you may fall asleep at 6 pm and wake up at 3 am.
  • Shift work disorder: This sleep disorder is common in people who frequently work shifts, particularly a combination of night-time and daytime shifts. This can disrupt your body’s natural circadian rhythm.


This category of sleep disorder is characterised by unusual physical events that occur before or during sleep. It can include abnormal movements (such as sleepwalking), sleep talking or expressing emotions, such as laughing, crying or screaming, during sleep. Some people with parasomnia experience a sleep-related eating disorder, where they eat or drink while asleep (or partially awake).

What are the Symptoms of a Sleep Disorder?

There are many potential symptoms of sleep disorders. The symptoms you experience can vary significantly depending on the type of sleep disorder you experience. 

Because the symptoms of a sleep disorder can vary considerably, it is recommended that you consult a medical professional if you experience any of the symptoms listed below.

  • Difficulties falling asleep (including an inability to fall asleep).
  • Sleep disturbances throughout the night.
  • Symptoms that disturb your sleep, including night-time panic attacks, nightmares or night-time psychosis.
  • Lying awake for extended periods of time.
  • Sleeping excessively.
  • Extreme daytime sleepiness.
  • Difficulties waking up.
  • Feeling tired when you wake up (suggesting your sleep was non-restorative).
  • Pauses in breathing during sleep or waking up breathless.
  • Choking or gasping during your sleep.
  • Irregular sleeping/waking patterns.
  • Falling asleep during the day with no warning.
  • Sleepwalking.
  • Sleep talking.
  • Bedwetting (more common in children).
  • Grinding or clenching your teeth during sleep.

You may also experience other symptoms, which when occur with at least one of the symptoms listed above, can be indicative of a sleep disorder.

These can include:

  • Feeling tired or fatigued.
  • Feelings of stress, anxiety or depression.
  • Low alertness and difficulties concentrating.
  • Reduced emotional capacity.
  • Feeling irritable and experiencing mood disturbances.
  • Low energy levels.
  • Impaired daytime functioning.
  • Excessive daytime sleepiness.
  • Impaired cognitive performance.
  • Frequent headaches.
  • Social withdrawal.
  • Slower reaction times.
  • Poor attention span.
  • Impaired judgement and difficulties making decisions.
  • Memory difficulties.

How is a Sleep Disorder Diagnosed?

Although many people experience difficulties sleeping at some point in their lives, if you experience disordered sleeping on a regular basis (i.e. multiple times per week), or if your sleeping difficulties last for more than a few weeks, you may have a sleep disorder. To be formally diagnosed with a sleep disorder, you will likely need to experience symptoms at least three times per week for a minimum of three months.

If you suspect you may be experiencing a sleep disorder, your first step will be to visit your GP or primary healthcare physician. Your doctor will first ask you to explain your symptoms. It can be helpful if you keep a sleep diary (where you track and monitor your sleep and your sleep habits and document any sleep problems). Your doctor may also perform a physical examination, take a detailed medical history and look at any medications you are taking, to ensure your symptoms cannot be attributed to another source. 

If your doctor thinks your symptoms are consistent with a sleep disorder, they may issue you with a sleep questionnaire. This is designed to gather additional information about your sleep and the sleep difficulties you are facing. Depending on your symptoms and the type of sleep disorder your GP suspects you may be experiencing, you may then be referred to a sleep clinic to undergo a sleep study. 

A sleep study, also known as a polysomnography, is a type of study that takes place overnight and examines your sleep.

Sensors will be attached to different parts of your body to record:

  • Your oxygen levels.
  • Your brain waves.
  • Your breathing patterns.
  • The movements of your chest and abdomen.

The sleep study can monitor your sleeping patterns and how long it takes you to fall asleep and identify how frequently you wake up in the night. The sleep study can also examine the quality of your sleep by looking at how long you spend in each sleep stage (e.g. in the non-rapid eye movement (NREM) and rapid eye movement (REM) stages).

Because each sleep disorder is characterised by significantly different symptoms and implications, your doctor will consider multiple factors before making an official diagnosis.

Feeling tired and fatigued a symptom of a sleep disorder

How is a Sleep Disorder Treated?

Once you have received a diagnosis, your doctor will create an individualised treatment plan. Your treatment plan will be created based on multiple factors, including:

  • The sleep disorder you are diagnosed with.
  • The severity of your sleep disorder.
  • Your age.
  • Any other health conditions you have, including mental health conditions.
  • Any medication you currently take.

The most common treatment options for sleep disorders are:

Cognitive Behavioural Therapy for Insomnia (CBT-I)

CBT-I can be an effective treatment for insomnia and other sleep disorders. It can help you to identify any thoughts, feelings or behaviours that are causing or contributing to your sleep disorder and help you to identify the root cause of your condition. CBT-I can also address the stress and anxiety, dysfunctional thoughts and adverse emotions you may experience in relation to sleep.

Sleep Education

Some people with a sleep disorder have an incorrect understanding of sleep and positive sleep behaviour that can exacerbate their symptoms. These misconceptions often revolve around sleep patterns, healthy sleep behaviour, and overall sleep well-being. Sleep education can offer valuable insights into how to create healthier habits that are more conducive to improved sleep quality and how to improve your sleep environment. For example, you can improve your evening routines, minimise your screen time before bed, introduce soft lighting and furnishings to your bedroom and prioritise your mental and physical well-being. Moreover, sleep education can play a role in alleviating any stress or anxiety you experience in relation to sleep.


Depending on the type of sleep disorder you are diagnosed with, your doctor may recommend medication. For example:

  • Sedative medication for severe insomnia.
  • Melatonin supplements for circadian rhythm disorders.
  • Iron supplements for an iron deficiency that is causing RLS.
  • Continuous positive airway pressure (CPAP) for OSA.
  • Anti-depressant medication.

Relaxation Techniques

Stress reduction and relaxation techniques can be beneficial for alleviating stress and anxiety, easing bodily tension, and creating a sense of calm and control. Various relaxation techniques can be incorporated into your daily routine, including:

  • Deep breathing: Deep breathing techniques have proven effective in reducing stress levels, alleviating body tension, and helping you manage anxiety and panic. Deep breathing sends a signal to your brain to relax. Integrating deep breathing into your daily practices, particularly in the lead-up to going to sleep, can improve your well-being and your sleep. It also has the added benefit of increasing melatonin levels, promoting relaxation, and supporting better sleep.
  • Meditation: This can be a helpful tool to teach you how to control your breathing and manage your body’s responses to stress and anxiety. It can also help you to direct your attention away from any disruptive thoughts. Meditation can facilitate both physical and mental relaxation and reduce your cortisol levels, which are associated with heightened stress, while simultaneously increasing melatonin levels, contributing to improved sleep.
  • Progressive muscle relaxation (PMR): PMR involves gentle breathing paired with systematic tension release in different muscle groups. This approach promotes body relaxation and helps you to release any lingering tension in your body, which could be contributing to your sleep disorder.
  • Autogenic training: This relaxation method aims to help you relax your body, reduce tension and reduce anxiety through the repetition of specific phrases. By creating a calming sensation in different areas of your body, autogenic training induces a relaxed state and creates feelings of heaviness and warmth.
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About the author

Nicole Murphy

Nicole Murphy

Nicole graduated with a First-Class Honours degree in Psychology in 2013. She works as a writer and editor and tries to combine all her passions - writing, education, and psychology. Outside of work, Nicole loves to travel, go to the beach, and drink a lot of coffee! She is currently training to climb Machu Picchu in Peru.

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