Insomnia or difficulty with sleeping is a common problem that has often multifactorial causes. At any one time, approximately 30% of the population are affected by significant insomnia with higher rates in older adults and in those with psychiatric disorders and certain medical and neurological conditions.
Persistent sleep loss or poor quality sleep can cause irritability, daytime sleepiness, poor concentration and difficulty with memory. It has also been associated with anxiety, depression, alcohol and substance misuse, poor resistance to infection and increased likelihood of daytime accidents. Some patterns of sleep loss such as ‘shift work disorder’ have been linked with an increased risk of peptic ulcer and heart disease. Furthermore, sleep deprivation in some studies has been linked to an increased risk of diabetes, cancer and mortality.
Sleep time for adults varies from about 7-9 hours with the average being about seven hours. Insomnia is characterised by either repeated difficulty with falling asleep (normally takes less than 30 minutes), maintaining sleep or impaired quality of sleep due to interruptions or awakenings.
With increasing age, early morning wakening is more common and may be due to changes in our circadian rhythm as a result of alterations in the hypothalamus in the brain. In fact, beginning in middle age, there is less time spent in ‘deep’ or ‘slow wave’ sleep, a reduction in overall sleep duration and also sleep efficiency (the proportion of time when in bed sleeping).
In many cases, there are secondary or co-morbid causes of insomnia that may require specific treatments. Indeed, over 90 sleep disorders have been described and whilst many are uncommon, some can be easily missed and require specialist investigations. In some instances, addressing lifestyle or environmental factors alone can significantly improve sleep.
Insomnia lasting for one month or more should be fully assessed. The pattern of sleep loss and frequency as well as other features may help identify the aggravating factors and causes.
Some medications can cause insomnia including those used for cardiac disease and should be reviewed. A number of practical measures should be looked at, such as maintaining good sleep hygiene and addressing factors like room temperature (avoid hot rooms), high noise levels and too much lighting.
Caffeine or stimulants including nicotine from cigarette smoking should be avoided from about 4pm onwards as should exercise for about 2-3 hours prior to going to bed. While alcohol is a sedative and may help you fall asleep, it impairs your sleep quality and acts as a diuretic, meaning it may lead to you feeling less well rested and having to get up to go the toilet during the night. In particular, this can be problematic in males with prostatism where avoiding fluids in the early evening (after about 7-8pm) and actively voiding (to empty the bladder) before going to bed may help.
Sleep restriction or reducing the time spent in bed to when one only sleeps may also be helpful. Time in bed can be increased by about 15 minutes every week, aiming for 90% of the total time spent in bed sleeping. Try and go to bed when sleepy and aim to wake at a consistent time every morning. Consider going to another room if unable to sleep after 20 minutes, remove clocks visible from your bed and try and avoid using your room for other purposes.
Cognitive behavioural therapy which focuses on changing false beliefs and attitudes about sleep has been shown to produce more long-term improvement in sleep than hynotics or sleeping tablets. It can increase total sleep and deep sleep time and the affect appears additive when used in combination with other measures.
Some medical conditions can cause insomnia and may require specific treatment. Restless leg syndrome which occurs in up to 15% of older adults is characterised by the intense and uncomfortable urge to move your legs, usually in the evening and especially at night. Symptoms are partially or totally relieved by walking or stretching.
Whilst the cause is not known, it usually responds to medications. It should be distinguished from night cramps in the legs which are often successfully treated with quinine tablets.
Obstructive sleep apnoea (which is more common in those who are overweight) is associated with multiple episodes of breathing cessation due to transient blockage of the upper airway and results in dips in oxygen levels during sleep. It leads to daytime sleepiness and frequently headaches but can also cause cognitive impairment and cardiovascular disease.
Whilst occurring in only about 5% of the population, it is often missed and requires a formal sleep study to diagnose. However, it can be successfully treated with positive pressure ventilation devices.
Sleeping tablets may be used for insomnia but are associated with tolerance, dependence, withdrawal symptoms and in particular cognitive impairment and daytime sedation in the elderly. In general, they should be instituted only after other measures have been tried and their use where possible should be limited to about four weeks to avoid the above problems.
Melatonin has been shown to improve several aspects of sleep in some studies, but there is no overall evidence that it is consistently affective. Finally, if depression or anxiety is contributory to insomnia then antidepressants should be considered.
If you have persistent insomnia, then you should visit your GP for a full assessment.
Dr Kevin McCarroll is a consultant physician in geriatric medicine in St James’s Hospital, Dublin.