Epidemiology^[2]

• Estimates of prevalence of insomnia vary according to the definition used. Studies indicate that one third of adults in Western countries experience difficulty with sleep initiation or maintenance at least once a week, and 6-15% are thought to meet criteria of insomnia in that they report sleep disturbance as well as significant daytime dysfunction.
• Prevalence is between 1.5 and 2 times higher in women than in men.
• Insomnia is a long-term disorder and many people have had insomnia for more than two years.
• Approximately half of all diagnosed insomnia is related to a psychiatric disorder.
• The incidence increases in men and women as they get older.

Aetiology^[2]

• Primary insomnia (no identifiable underlying cause) is a diagnosis of exclusion and accounts for only 12-30% of chronic insomnia.^[4][5]
  
  
• Temporary insomnia is associated with stress, personal problems, something that changes sleep patterns such as the birth of a child or starting shift work, painful physical illness, depression, anxiety, and excessive alcohol or caffeine. In some people, the acute insomnia persists into a chronic state.
• Circadian rhythm disorders: sleep disorders caused by a mismatch between circadian rhythms and required sleep-wake cycle, which may sometimes be due to an individual lifestyle, including work and travel schedules, that conflicts with the internal clock.

Physiological

• Poor sleep hygiene, eg caffeine, daytime naps.
• Poor sleeping environment, eg noise, light.
• Disturbed sleep routine, eg shift work, jet lag, intellectual or physical activity immediately prior to going to bed.

Physical and psychological

• Movement disorders, eg restless legs syndrome, Parkinson's disease, cerebrovascular disease.
• Respiratory and cardiac disorders, eg obstructive sleep apnoea, dyspnoea, and coughing.
• Pain, eg arthritis, headaches.
• Nocturia, eg benign prostatic hyperplasia, diabetes mellitus or diabetes insipidus, diuretics.
• Endocrine, eg hyperthyroidism (sweats).
• Perimenopausal symptoms.
• Other physical symptoms, eg pruritus, leg cramps.
• Psychological/psychiatric, eg depression, dementia, anxiety, bereavement, chronic alcohol abuse, other substance abuse.
• Parasomnias - unusual episodes or behaviours occurring during sleep which disturb the patient or others, eg nightmares, night terrors, sleepwalking.

Pharmacological

• Drug withdrawal, eg hypnotics, alcohol (reduces the time to onset of sleep, but disrupts it later in the night).
• Chronic benzodiazepine misuse.
• Some antidepressants, especially selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs).
• Sympathomimetics
• Corticosteroids (agitation).
• Beta-blockers.

Assessment^[6]

• Sleep diaries: these provide a record of the sleep pattern over one to two weeks. Sleep diaries can often identify sleep trends or predominant sleep patterns. Sleep diaries can be used as a starting point for managing insomnia and for monitoring progress.
• Physical and psychological examination may be useful to identify a possible underlying cause. Further investigations may also be indicated, eg blood tests for hyperthyroidism and low ferritin levels, which may be associated with restless legs syndrome.
• Polysomnography (overnight sleep study): this measures brain and muscle activity and assesses oxygen saturation overnight. It can be used to confirm sleep apnoea and limb movement disorders or restless legs syndrome.

Management

Treatment is appropriate when insomnia causes significant personal distress or marked impairment.^[2] Those affected, commonly consult doctors, often with the expectation of a 'sleeping tablet'. 10 million prescriptions every year are dispensed for hypnotics.^[4] The Committee on Safety of Medicine and the Royal College of Psychiatrists have long advised that hypnotic drugs should be limited to short courses for acutely distressed patients, and avoided in the elderly.^[7][8][9]

If any uncertainty exists about the diagnosis or if any safety concerns have been identified (eg excessive daytime sleepiness or parasomnias causing injuries), patient referral for an assessment by a sleep specialist is indicated.

Sleep hygiene advice^[6]

• About 30% of patients with primary insomnia will improve with sleep hygiene advice alone.
• Limit caffeine to one cup of coffee in the morning, avoid alcohol and cigarettes at night, and reduce or avoid any other substances that can affect sleep.
• Avoid napping during the day
• Regular daily exercise can help improve sleep, but exercise late in the evening should be avoided.
• Advise to do only quiet, relaxing activities before bedtime. Heavy meals just before bedtime should be avoided but a light snack may be helpful.
• Ensure that the bedtime environment is comfortable and conducive to sleep.
• Using computers: looking at a computer screen in the hours before bed may delay sleep onset.
• Looking at a clock during awakenings can increase frustration at being awake and so further delay sleep.
• Advise restricting their total time in bed to their estimated total sleep time.
• Avoid going to bed until drowsy and ready to sleep.
• If not asleep within 15-20 minutes, the person should get out of bed and return only when drowsy.
• Use the bed/bedroom only for sleep.
• Get up from bed at the same time each day.

Cognitive behavioural therapy (CBT)^[2]

• CBT-based treatment for chronic insomnia, including sleep restriction and stimulus control, is effective and should be offered to patients as a first-line treatment, either individually or in small groups. However, a lack of trained staff limits the scope for delivering these treatments in primary care.^[4]
• CBT has been found to be as effective as prescription medications for short-term treatment of chronic insomnia.
• The beneficial effects of CBT may last well beyond the end of active treatment.

One study found that behavioural treatment for insomnia, consisting of individualised behavioural instructions delivered in two intervention sessions and two telephone calls, provided a simple, effective and durable intervention for chronic insomnia in older adults.^[10]

Pharmacological treatments^[2]

• Currently marketed hypnotic drugs are effective in promoting sleep in the short term but there is little good evidence for their long-term efficacy and there are serious concerns regarding the risk of dependence when these drugs are used in this way.^[4][11]
• Z drugs (zopiclone, zaleplon, zolpidem) and short-acting benzodiazepines (nitrazepam, loprazolam, lormetazepam, temazepam) are effective for insomnia.
• Problems relating to safety (adverse events and carry-over effects) are fewer and less serious using drugs with short half-lives. Nitrazepam is longer-acting compared to loprazolam, lormetazepam and temazepam and so is more likely to give rise to 'hangover' effects the next day, and repeated doses may become cumulative. However, they are less likely to cause withdrawal phenomena than the short-acting benzodiazepines.^[8] Diazepam (long-acting) is sometimes used as a single nocturnal dose to treat daytime anxiety associated with insomnia.^[8]
• The National Institute for Health and Clinical Excellence (NICE) recommends that there is little compelling evidence to distinguish between the Z drugs and shorter-acting benzodiazepines clinically, so that the cheapest drug should be used - usually temazepam. Only if side-effects specific to that drug develop does NICE suggest switching to a different hypnotic. There is no evidence of benefit of switching between Z-class drugs.^[1]
• Prolonged-release melatonin improves sleep onset and quality in patients aged over 55 years.
• Antidepressants: there is limited evidence for efficacy of doxepin, trimipramine, trazodone, or paroxetine in insomnia. Antidepressants may affect a wide range of brain receptors and have longer-lasting carry-over effects than traditional hypnotic drugs - antidepressants are associated with increased risks of road accidents especially early in treatment in depression.
• Antipsychotics: olanzapine and quetiapine improve sleep in healthy volunteers. Quetiapine improves sleep in primary insomnia. Side-effects are common.
• Sedating antihistamines have a limited role in psychiatric and primary care practice for the management of insomnia. Promethazine and diphenhydramine are widely purchased over the counter but good evidence of their efficacy is lacking, hangover effects are common and rebound insomnia can occur after prolonged use.^[3][4]
• Valerian and other herbal remedies have very little evidence of efficacy and are not recommended.^[4]

Cautions

• Hypnotic drugs are associated with tolerance, dependence, withdrawal syndrome and with rebound insomnia on cessation.^[6] However, studies suggest that dependence (tolerance/withdrawal) is not inevitable with hypnotic therapy up to one year with some drugs, including zolpidem.^[2] See separate article Benzodiazepine Dependence.
• The elderly are most at risk of becoming ataxic, confused and/or falling due to hypnotic treatment, as they eliminate the drugs more slowly, are more susceptible to CNS depression and are more likely to be using potentially interacting drugs. The use of long-acting benzodiazepines and some Z drugs seems to be associated with an increased risk of falls and hip fractures in elderly patients. A meta-analysis looking at the risks and benefits of sedative use in the over-60s found a marginal improvement in sleep quality outweighed by risk of adverse event. This is particularly marked where patients have additional risk factors for cognitive or psychomotor adverse events.^[12]
• Children: use of hypnotics in children is not normally justified - the exceptions being occasional use for night terrors and sleep-walking.^[8]
• Potential for abuse: all hypnotics have the potential for abuse. Temazepam is the most commonly abused of these drugs, but other benzodiazepines and, more recently, zopiclone have all been implicated in illicit drug use.^[13]
• Driving: hypnotics impair judgement and increase reaction times, so affecting the ability to drive or operate machinery, and increasing risk of road traffic accidents. Patients must be aware of this and the fact that hangover effects of a night dose may still manifest themselves the following day. DVLA advises that any patient suffering from excessive awake-time sleepiness, regardless of cause (including due to the insomnia itself), should cease to drive until there is satisfactory control of symptoms.^[14] Persistent use or dependency on benzodiazepines will lead to licence refusal or revocation for a minimum of one year.^[13]

Complications of insomnia^[2]

• Quality of life is impaired in insomnia.
• There is an increased risk of subsequent first episode or relapse of depression and anxiety disorder in those with a pre-existing persistent insomnia.
• Primary insomnia is associated with poor objective sleep and impaired objectively measured daytime performance.
• There is an increased risk of hypertension in insomnia with objectively measured short sleep duration.
• Absenteeism, accidents at work and road accidents are increased in insomnia.