RESUMEN
BACKGROUND: Sleep disorders are classified into six main categories: insomnias, circadian rhythm disorders, sleep-related movement disorders, sleep-related breathing disorders, hypersomnias and parasomnias. The aim of this article is to shed light on differences between these categories with respect to symptom patterns. MATERIAL AND METHODS: The main sources of information are the diagnosis manual published by the American Academy of Sleep Medicine in 2005 and papers identified through non-systematic searches in Pubmed. RESULTS: Long sleep onset latency is most common in patients with insomnia, delayed sleep phase syndrome and restless legs while nightly awakenings are most common in patients with insomnia, restless legs and the sleep apnoea syndrome. Excessive daytime sleepiness is most pronounced in patients with hypersomnia, sleep apnoea syndrome and delayed sleep phase syndrome, whereas patients with insomnia rarely have this problem. Fatigue is a common feature of all sleep disorders, especially insomnia. The diagnosis of insomnia, circadian rhythm disturbances, restless legs and most parasomnias is mainly based on anamnestic data. Objective sleep recordings are necessary to diagnose sleep apnoea syndrome, hypersomnia and periodic leg movement during sleep. INTERPRETATION: The six sleep disorder categories differ substantially with respect to symptom patterns. Sleep disorders can often be distinguished from each other by use of anamnestic data without resorting to further assessment, but objective sleep recordings are needed for accurate diagnosis of some patients.
