Sleep and Sleep Disorders

Sleep and sleep disorders form an overarching framework for the clinical approach to disordered sleep. Insomnia is the commonest sleep complaint encountered in clinical practice.

This entry provides the general principles of sleep physiology, structured assessment, and the foundational, broadly applicable management approach (particularly for insomnia). It underpins the more specific, individual sleep disorder entries.

The framework encompasses these groups of disorders:

• insomnia disorder;
• the hypersomnias (including narcolepsy);
• circadian rhythm disorders;
• parasomnias;
• sleep related movement disorders (including restless legs syndrome);
• sleep related breathing disorders (obstructive sleep apnoea).

Sleep physiology and classification

• Normal sleep architecture comprises cyclical progression through non-rapid eye movement sleep (further subdivided into stages reflecting progressively deeper sleep) and rapid eye movement sleep. Each cycle lasts approximately ninety minutes and recurs several times through a typical night.
• The proportion and distribution of sleep stages vary across the lifespan. They are disrupted by numerous underlying sleep disorders and other medical, psychiatric and environmental factors.
• Insomnia disorder, the commonest specific sleep complaint, is characterised by persistent difficulty with sleep initiation, maintenance, or early morning waking, together with associated daytime impairment, occurring despite adequate opportunity for sleep.
• Chronic insomnia (persisting three months or longer) is frequently perpetuated by maladaptive behavioural and cognitive factors. These include excessive time spent in bed, irregular sleep scheduling, and anxious preoccupation with sleep itself.
• These factors develop and persist even after any original precipitating factor has resolved. This is the principle underlying the specific, evidence based behavioural treatment approach.
• Secondary insomnia reflects an underlying medical or psychiatric condition, medication effect, or another primary sleep disorder as the driving cause. It must be considered, identified and addressed, because the management approach differs fundamentally from primary, behaviourally maintained chronic insomnia.

• Insomnia presents with difficulty falling asleep, frequent or prolonged nocturnal waking, or early morning waking with inability to return to sleep. Daytime consequences include fatigue, impaired concentration, mood disturbance, and reduced overall functioning and quality of life.
• A detailed sleep history forms the essential foundation of assessment. It covers typical sleep and wake timing, sleep environment, pre-sleep routine and behaviour, daytime napping pattern, caffeine, alcohol and substance use, and the nature and duration of any sleep difficulty.
• Screen for symptoms suggesting an alternative or underlying primary sleep disorder: loud snoring or witnessed apnoea suggesting obstructive sleep apnoea, uncomfortable leg sensations suggesting restless legs syndrome, or excessive daytime sleepiness with cataplexy suggesting narcolepsy.
• Screen for coexisting or underlying medical and psychiatric conditions frequently associated with or causative of secondary insomnia. These include depression, anxiety disorders, chronic pain conditions, and specific medical conditions (including hyperthyroidism and menopause related symptoms).
• Include a full medication review, given the numerous medications capable of disrupting normal sleep architecture.
• A sleep diary, maintained by the patient over one to two weeks, captures bedtime, estimated sleep onset time, nocturnal wakings, final waking time, and daytime napping. It provides valuable, objective longitudinal information supporting both diagnosis and monitoring of treatment response, particularly relevant to the structured behavioural treatment approach.

• Diagnosis of insomnia disorder is predominantly clinical, based on the characteristic history of persistent sleep difficulty with associated daytime impairment. Formal sleep laboratory investigation (polysomnography) is not routinely needed in straightforward presentations.
• Reserve polysomnography for cases where an alternative primary sleep disorder (obstructive sleep apnoea, narcolepsy, a specific parasomnia, or a sleep related movement disorder) is suspected from the clinical history. Also use it where the diagnosis and underlying cause of the sleep disturbance remain genuinely unclear despite full clinical assessment.
• Actigraphy (a wrist worn device providing objective estimation of sleep and wake patterns based on movement) may be used as a further, less resource intensive adjunct to subjective sleep diary data in some clinical contexts. It provides additional objective information regarding sleep pattern and timing.
• Screening questionnaires support structured assessment and identification of relevant underlying or coexisting factors requiring their own specific evaluation and treatment. These are depression and anxiety screening tools, and validated screening tools for obstructive sleep apnoea risk and excessive daytime sleepiness.

• Cognitive behavioural therapy for insomnia is the first line, most strongly evidence supported treatment for chronic insomnia disorder. It demonstrates durable, sustained benefit superior to pharmacological treatment in the great majority of patients with chronic insomnia.
• It is a structured combination of four components, listed next.
• Sleep restriction therapy: initially restrict time in bed to more closely match actual sleep duration, then gradually extend as sleep efficiency improves.
• Stimulus control: strengthen the association between the bed and sleep specifically, including advice to leave the bed if unable to sleep after a defined period rather than remaining awake in bed.
• Sleep hygiene education, and cognitive techniques addressing unhelpful, anxiety perpetuating beliefs about sleep.
• General sleep hygiene advice is a useful, broadly applicable adjunct. It includes maintaining a consistent sleep and wake schedule, avoiding caffeine and alcohol close to bedtime, ensuring an appropriate sleep environment (dark, quiet, comfortable temperature), and avoiding significant screen use or stimulating activity immediately before bed.
• It is generally insufficient as a standalone treatment for established, chronic insomnia disorder. The structured cognitive behavioural approach is required for optimal, durable benefit.
• Pharmacological treatment, where used, is generally reserved for short term, adjunctive use. Prolonged use carries a risk of dependency and tolerance, and long term outcome is generally inferior to cognitive behavioural therapy.
• Options include short courses of a Z drug hypnotic (zolpidem or zopiclone) or, particularly for insomnia with a significant coexisting anxiety or depressive component, a sedating antidepressant. Use judiciously with clear, time limited treatment goals, not as an indefinite, standalone long term strategy.
• Melatonin has a specific, evidence supported role for circadian rhythm related sleep disturbance, including jet lag and delayed sleep phase disorder.
• It may have some benefit in insomnia in certain specific populations (including older adults and those with autism spectrum disorder). Evidence for benefit in typical, primary chronic insomnia disorder is more limited.
• Identify and treat any underlying secondary cause (an alternative primary sleep disorder, an underlying medical or psychiatric condition, or a contributing medication). Addressing this driver frequently produces substantial improvement in the secondary insomnia without necessarily requiring the full, structured cognitive behavioural protocol.
• The structured approach remains appropriate and beneficial as an adjunct even where a relevant underlying or contributing condition has been identified and addressed.