Primary sleep disorders

 

Primary sleep disorders are common but up to 50% go under-reported in the general population (Leger D, 2007). The most frequently occurring primary sleep disorders in older adults are insomnia, sleep disordered breathing, restless legs and REM sleep-behaviour disorder (REMSBD).

 

 

Insomnia

 

Insomnia is defined as a difficulty in initiating or maintaining sleep.

It is the most frequent sleep complaint in older age and predicts greater use of health services and hospitalisation (Kaufmann CN, 2013)

 

Whilst a primary sleep disorder, it is often co-morbid with chronic physical and mental illness. In particular depression has been shown to predict insomnia (Cole MG, 2003) and untreated insomnia can result in depression. Treatment of insomnia should therefore take into account the various possible contributors.

Cognitive behavioural therapy (CBT) is the most effective behavioural treatment for chronic insomnia; benefit may last up to two years after treatment (Morin CM, 1999) and be as effective as pharmacological therapy (NIHSS, 2005).

 

Older people account for 40% of all hypnotics prescribed and although a variety of drug classes including benzodiazepines, antipsychotics, anticonvulsants, antidepressants and antihistamines have been used to treat insomnia, there is no systematic evidence for efficacy of any class of medication (Koch S, 2006).

Benzodiazepine hypnotics are most commonly used for treatment of insomnia. They are effective in the short term (NIHSS, 2005) and should be considered in combination with behavioural therapy.

 

'Z-drugs' (zolpidem, zopiclone), thought to be safer hyponotics as they are non-benzodiazepine, have shown a reduction in sleep latency, both polysomnographically and subjectively. However sleep latency shows a significant response to placebo. Chronic use of the `Z-drugs' at low or high dose carries a risk of increased adverse events (Huedo-Medina TB, 2012).

 

Caution is advised with use of hypnotics as 80% of insomnia in older people is chronic and hypnotics lose effectiveness after weeks of continuous use (Curran HV, 2003).

The risks associated with long-term use of hypnotics outweighs their benefit.

Benzodiapezines must be reviewed and withdrawn gradually when no longer required or effective. Although concerns exist about rebound insomnia, there is little difference in subjective sleep quality in older people tapering off benzodiazepincs compared with those who continue on benzodiazepines (Curran HV, 2003).

 

Sleep Disordered Breathing

 

Sleep disordered breathing (SDB) refers to a spectrum of disorders: from snoring to apnoea.

SDB has a higher prevalence in older people, with an increased frequency among those with dementia or living in nursing homes (Young T, 2002).

Increased age, male gender and obesity are the main risk factors for SDB. However other factors including use of sedatives, alcohol consumption, smoking, race and upper airway configuration increase the risk of Sleep Disordered Breathing (SDB) (Young T, 1993).

SDB is associated with impaired cognition (Weaver TE, 2007) and older adults with SDB are more functionally impaired than those with insomnia alone (Goonerathe NS, 2006).

Older adults also have a greater risk of cardiovascular disease (Shahar E, 2001).

 

Common symptoms of SDB are snoring and excessive daytime somnolence.

Diagnosis is confirmed with overnight oximetry and sleep studies.

Continuous positive airway pressure (CPAP) is a proven treatment for SDB: it reduces apnoea and hypopnoea, improves sleep architecture and cognition, and reduces symptoms and cardiovascular risk (Weaver TE, 2007).

However its effect on mortality has not been defined.

 

 

Restless legs syndrome and periodic limb movements in sleep.

 

Restless legs syndrome (RLS) is characterised by dysaesthesia of the legs resulting in the urge to move. This occurs when relaxed, and is more frequent in the evenings and at night.

Whilst the majority of RLS is idiopathic, it is associated with iron deficiency, uraemia, peripheral neuropathy and radiculopathy. In the former two associations, symptoms abate when the underlying abnormality is corrected. Patients generally present due to disrupted sleep.

 

Periodic limb movements in sleep (PLMS) may present in a similar manner.

PLMS, also known as nocturnal myoclonus, is characterised by frequent stereotyped movements of the legs, generally extension of the big toe and flexion at the ankle and knee.

It is a symptom associated with RLS, SDB, REMSBD and narcolepsy and is considered pathological when more than five movements occur per hour.

 

Both RLS and PLMS are more common in older age. RLS has a prevalence of 9-20% in those aged over 70 years and PLMS occurs in up to 86% of older people with sleep disorders (Homyak M, 2004).

 

A detailed history is vital to diagnose RLS.

 

The dopamine agonists ropinirole and pramipexole are licensed treatments for RLS.

Other drugs, such as levodopa and anti-convulsants, may be effective albeit a non-licensed indication for these drugs.

 

 

Rapid eye movement sleep behaviour disorder

 

Rapid eye movement sleep behaviour disorder (REMSBD) results from an absence of the normal muscle atonia that is a feature of REM sleep.

Patients with the condition are classically described as "acting out their dreams", including kicking, punching and shouting. The patient is unaware of their actions, which can result in injury to the patient or their bed-partner and often drive the bed partner to move to another bed / bedroom.

 

As with RLS, REMSBD occurs more frequently in older people, with a greater prevalence amongst older men.

Although the aetiology of REMSBD is unknown, up to 57% are associated with dementia, Parkinson's disease or multiple system atrophy (Olson EJ, 2000).

 

No specific treatment has been shown to alleviate the symptoms of REMSBD.

Cautious use of low dose clonazepam is more effective and more commonly used, than other options including dopaminergic drugs and SSR1 antidepressmts (Aurora RN, 2010).