Pharmacological management

Diagnosis and management of both the insomnia and if present, its cause is important where possible. Traditionally, the treatment aim in primary insomnia has been to reduce insomnia symptoms alone. In secondary insomnia, the focus has been treatment of the associated condition hopefully leading to a resolution of the insomnia. However, as recently identified by the American Psychiatric Association³, it is often difficult to establish the precise nature of the relationship between the insomnia and a comorbid condition. Therefore management may need to be more mindful of both conditions, with the insomnia considered as a target for intervention rather than merely a symptom of another medical problem.

A drug used to induce sleep is described as a 'hypnotic'. Although hypnotics can provide relief from the symptoms of insomnia, they do not treat any underlying cause if one is present.

Should non-pharmacological approaches prove ineffective then a hypnotic medication may be considered appropriate for the management of severe insomnia interfering with normal daily life. It is recommended that traditional hypnotics (benzodiazepine / Z-drugs) should only be prescribed for short periods of time and, in strict accordance with their licensed indications⁶³.

A number of different classes of medication are licensed as hypnotics. These include benzodiazepines, Z-drugs (also known as non-benzodiazepine hypnotics or Z hypnotics), chloral derivatives, clomethiazole, anti-histamines and the naturally occurring hormone, melatonin.

Generally, hypnotics decrease time to sleep onset and episodes of waking in sleep as well as increasing total sleep time⁸³. Benzodiazepines, Z-drugs, chloral derivatives and clomethiazole all act by binding to the GABA_A receptor, enhancing the effect of GABA¹³³² resulting in sedation. (Gamma-aminobutyric acid [GABA] is an inhibitory neurotransmitter that helps induce relaxation and sleep²⁷). Antihistamines act as antagonists at the H1-receptor and cross the blood-brain barrier also causing sedation⁶⁶.

Melatonin, on the other hand, is a hormone that is produced by the pineal gland and, as a result of its activity at melatonin-specific receptors – primarily MT1 and MT2 - regulates the circadian rhythm of sleep⁹⁹. It promotes sleep initiation and helps to reset the circadian clock, allowing uninterrupted sleep. It has also been shown to improve next day functioning³⁰, quality of sleep (QOS) and quality of life (QOL)⁴¹⁹⁵. Although its effects are fairly modest, it has no known motor side-effects⁹⁷.

What constitutes the ideal hypnotic has been discussed for decades. Whilst certain characteristics are self evidently beneficial (eg. no residual effects, dependence, interactions, etc.), some will vary between patients. For example, drugs with a longer half-life may be effective at maintaining sleep throughout the night but may cause residual ‘hangover’ effects in the morning⁹⁷.