Sleep disorders

A bad night’s sleep can cause tiredness the next day but won’t generally affect a person’s health if it is an occasional occurrence. A few sleepless nights in a row, however, can have much more of an impact, causing difficulty concentrating and making decisions, and may lead to low mood and anxiety about not being able to sleep the next night. 

There is also the possibility of falling asleep during the day – particularly dangerous for those performing skilled tasks such as operating heavy machinery or driving.

The road safety charity Brake says that 10-20 per cent of all crashes are caused by driver fatigue with most taking place on motorways and dual carriageways. Anyone with a sleep disorder has a duty to inform driving agencies if it is likely to have an adverse effect on driving capability.

Insomnia is probably the best known sleep disorder. It is defined as difficulty in getting to sleep or maintaining sleep, or experiencing early morning wakening or non-restorative sleep despite adequate opportunities. A key feature is impaired daytime functioning, such as the symptoms already described. 

Insomnia of less than three months’ duration – and typically only a few days or weeks – is regarded as short-term, whereas someone who experiences insomnia symptoms on at least three nights per week for three months or longer is regarded as having the chronic form of the disorder. 

Unlike many health conditions, the terms 'primary' (i.e. not attributable to an underlying cause) and 'secondary' (i.e. due to a comorbidity) tend not to be used as insomnia is considered a disorder in its own right (as opposed to a symptom) and associations with other conditions tend to be interactive in nature. As an example, depression may lead to insomnia symptoms, while insomnia may worsen already low mood.

The prevalence of insomnia is higher in females, older adults and those with long-term conditions such as COPD, heart failure, chronic pain and mental health conditions. Around half of people with diagnosed insomnia have a psychiatric comorbidity. 

As well as cognitive difficulties such as impaired memory and concentration, quality of life and functioning may also deteriorate with insomnia, leading to an increased risk of falls (notably in older people), decreased productivity at work and increased absenteeism. 

Mental health complications include anxiety, depression and substance misuse, and medical complications include an increased risk of cardiovascular disease and type 2 diabetes.