Sleep disorders

Epidemiology

Sleep disorders can affect people of all ages. The dyssomnias are generally more common in adults, and the parasomnias are more prevalent in children. All of these disorders can have an adverse affect on an individual's quality of life, and may be detrimental to their health and well-being.

Dyssomnias

Insomnia
Either transient or chronic insomnia affect approximately half of the adult population at some point in their lives. Anyone can be affected by insomnia, especially if they are going through a stressful period in their life. However, it is more common in women than in men, and more prevalent in the elderly.

Hypersomnia
Hypersomnias can be divided into two main types: apnoea and narcolepsy. Both are more common in women, people who work night shifts, and people who have a depressive illness. Both may also have a hereditary basis, as a person is more likely to have one of these conditions if a member of their family does. People are at greater risk of specifically having apnoea if they are obese and/or if they have other medical conditions, such as heart failure. Apnoea affects between 2-4% of people,(1) whereas narcolepsy affects 0.05-0.07% of the population.(2)

Circadian rhythm sleep disorders
The main circadian rhythm sleep disorders are jet lag syndrome, shift work sleep disorder, delayed sleep phase syndrome (DSPS) and advanced sleep phase syndrome (ASPS). Jet lag syndrome affects people flying across time zones, shift work sleep disorder affects people who work irregular hours, especially nights, DSPS is more common in younger people, and ASPS is more prevalent in those who are older.

Parasomnias

The different types of parasomnias are shown in the table below. The main types include sleepwalking and sleep terrors. Sleepwalking affects 15% of children aged 5-12, and sleep terrors are most likely to occur in 3-11 year olds. A person is more likely to experience either sleepwalking or sleep terrors if there is a family history of the disorder. This implies that these disorders may be hereditary.

References

1. Jennum P, Sjol A. Snoring, sleep apnea and cardiovascular risk factors in a 30-60 year-old population. The MONICA II study. Int J Epidemiol 199;22:439-44.

2. Hublin C, Partinen M, Kaprio J, et al. Epidemiology of narcolepsy. Sleep 1994;17(8 Suppl):S7-S12.