Overview of Sleep Disorders
We exist in different behavioural states – awake or asleep; and a third of our lives is spent sleeping! Sleep is as important to our health as eating, drinking and breathing. It allows our bodies to repair themselves and our brains to consolidate our memories and process information. Sleep is not just ‘time out’ from our busy routine. Lack of sleep can make us feel physically unwell as well as stressed and anxious, and it contributes to heart disease, premature ageing and road accident deaths among other problems.
Sleep is not a homogenous state, there actually being two states, Rapid Eye Movement Sleep (REM-Sleep) and Non Rapid Eye Movement (non-REM) sleep. All organ systems undergo major sleep-related changes, particularly the respiratory system and heart. Not surprisingly, a number of things can go awry during sleep, leading to a variety of sleep disorders.
Sleep problems are highly prevalent, affecting approximately 75% of adults and 25–40% of children across life time. The most recent edition of the International Classification of Sleep Disorders (ICSD-3, 2014) lists nearly 70 separate primary disorders of sleep. In addition, sleep is disrupted in a wide variety of general medical, psychiatric and psychological disorders.
Excessive daytime sleepiness
Sleepiness is a perception of the need to sleep. It can also be considered as the ability to fall asleep. Sleepiness manifests as yawning, eye rubbing, drooping of eyelids, and lapses of attention. The loss of muscle tone in sleep leads to head-nodding if the person is sitting or standing.
Daytime Sleepiness is the inability to remain awake and alert during the day time. If this causes concern or interferes with day-to-day functioning it is considered Excessive Daytime Sleepiness (EDS). When sleepiness occurs only in circumstances that require relatively little attention, it is considered as mild EDS. Sleepiness occurring while engaged in activities that require higher degrees of attention can have dangerous consequences. At times sleepiness can be overwhelming and can occur without warning when it is called a ‘sleep attack’.
It is common to feel a bit groggy immediately upon waking up from sleep. This state of sleep inertia usually lasts only for a few minutes, rarely exceeding 30 minutes. If sleep inertia is severe and lasts longer, it is known as sleep drunkenness. Those with severe sleep inertia find it difficult to wake up from sleep. They may repeatedly fall back asleep, and be irritable, aggressive or confused.
Insomnia
Insomnia is difficulty in falling asleep, staying asleep, waking up too early from sleep or feeling not refreshed after sleep. Most patients with insomnia complain of one or more of these symptoms. If these are associated with daytime symptoms such as fatigue, difficulty in attention, concentration, memory mood, etc., it is known as insomnia disorder.
Most of us would have experienced insomnia at some time in our lives. Approximately 10% of the population suffers from Chronic Insomnia Disorder.
Sleep Apnoea
Sleep Apnoea is a condition in which you develop ‘apnoea’ during sleep. Apnoea means ‘stoppage of breathing’. In fact, your breathing may not completely stop, but become very shallow, to the extent that you are not able to get adequate amount of air in to your lungs (technically known as ‘hypopnoea’).
Apnea and hypopnea can occur either because the air passage in your throat is obstructed (when it is known as ‘Obstructive’ sleep apnoea or OSA) or because your brain does not send signals to your chest muscles instructing the chest to expand to fill your lungs (known as ‘Central sleep apnoea’). Obstructive Sleep Apnoea is the commonest type of Sleep Apnoea.
Restless Legs Syndrome (RLS)
RLS is a common neurological sleep disorder affecting 10-15% of the population. Approximately 10% of patients with RLS have significant symptoms that would require medical intervention for control. If you answer ‘yes’ to the question ‘when you try to relax in the evening or sleep at night, do you ever have unpleasant, restless feelings in your legs that can be relieved by walking or movement?’ you are likely to have RLS.
RLS affects men and women and may start in childhood. It often runs in families.
Narcolepsy
Narcolepsy is perhaps the best known neurological sleep disorder. It usually starts in adolescence or early adult life and manifests as excessive sleepiness in the wake time. Patients with narcolepsy may also have ‘cataplexy’ – sudden loss of muscle power when emotionally excited, such as when you hear a joke or are taken by surprise.
Other features of narcolepsy include vivid dreams, sleep-related hallucinations, sleep paralysis and frequent interruption of sleep at night. Patients with narcolepsy may also have other sleep disorders such as obstructive sleep apnoea, restless legs syndrome and REM Sleep Behaviour Disorder.
Narcolepsy is perhaps the best known neurological sleep disorder. It usually starts in adolescence or early adult life and manifests as excessive sleepiness in the wake time. Patients with narcolepsy may also have ‘cataplexy’ – sudden loss of muscle power when one is emotionally excited, such as when you her a joke or are taken by surprise.
Other features of narcolepsy include vivid dreams, sleep-related hallucinations, sleep paralysis and frequent interruption of sleep at night. Patients with narcolepsy may also have other sleep disorders such as obstructive sleep apnoea, restless legs syndrome and REM Sleep Behaviour Disorder.
Circadian Rhythm Sleep Wake Disorders
The timing of sleep is determined by actions of our ‘body clock’ (Circadian Rhythm). Alterations of the Circadian Rhythm can cause various sleep complaints, of which the best known is ‘jet lag’.
Patients may experience insomnia at night, excessive sleepiness in the daytime, or irregular periods of sleep and wake through the 24-hour day.
The timing of sleep is determined by actions of our ‘body clock’ (Circadian Rhythm). Alterations of the Circadian Rhythm can cause various sleep complaints, of which the best known is ‘jet lag’.
Patients may experience insomnia at night, excessive sleepiness and in the daytime, or irregular periods of sleep and wake through the 24-hour day.
Sleep Walking
There are a number of other conditions that may cause abnormal movements in sleep. The commonest condition is Restless Legs Syndrome. Another condition closely related to RLS is Periodic Limb Movement Disorder of Sleep (PLMD).
Abnormal behaviors arising from sleep are known as parasomnias. Parasomnias occurring during NREM Sleep are known as NREM parasomnias. The best known NREM parasomnia is Sleep Walking, also known as somnambulism.
There are other types of NREM parasomnias including Sleep Terrors, Confusional Arousals, Sleep Related Eating and Sleep Sex (Sexsomnia).
Abnormal behaviors arising from sleep are known as parasomnias. Parasomnias occurring during NREM Sleep are known as NREM parasomnias. The best known NREM parasomnia is Sleep Walking, also known as somnambulism.
There are other types of NREM parasomnias including Sleep Terrors, Confusional Arousals, Sleep Related Eating and Sleep Sex (Sexsomnia).
Distressing Dreams
All of us dream during Rapid Eye Movement Sleep, although many do not remember the dreams. Nightmares are very vivid dreams that become disturbing as they unfold. All of us a familiar with the occasional nightmares.
The content of nightmares involves scenes of imminent physical danger or other distressing themes. They are usually associated with anxiety, fear or terror. Upon waking, the person is able to give a vivid description of the scenes of the nightmare.
All of us dream during Rapid Eye Movement Sleep, although many do not remember the dreams. However, dreams are often distressing when they are known as nightmares. All of us a familiar with the occasional nightmares.
Nightmares are very vivid dreams that become more disturbing as they unfold. The content of nightmares involves scenes of imminent physical danger or other distressing themes. They are usually associated with anxiety, fear or terror. Upon waking, the person is able to give a vivid description of the scenes of the nightmare.
Sleep Paralysis
Sleep paralysis (SP) is an inability to make voluntary movements, either as one falls asleep or when waking up from sleep. The person is unable to speak or move the body. Consciousness, memory and breathing are unaffected. An episode of SP may last seconds or minutes.
A person may recover quickly if spoken to or, touched during the episode. Occasional episodes of SP occurs in normal individuals. If it occurs frequently in the absence of narcolepsy, it is known as Recurrent Isolated Sleep Paralysis (RISP).
Abnormal movements in Sleep
There are a number of conditions that cause abnormal movements in sleep. The commonest condition is Restless Legs Syndrome. Another condition closely related to RLS is Periodic Limb Movement Disorder of Sleep (PLMD).
There are a number of other conditions that may cause abnormal movements in sleep.
Other Sleep Disorders
There are many other medical and neurological disorders that present with symptoms in sleep. Examples include sleep-related epilepsy, sleep related ‘acid reflux’ , sleep related headaches and others.
