References
Mahowald & Schenck. Insights from studying human sleep disorders. Nature (2005); 437(7063):1279-85. Bassetti et al., Lancet (2000); 356: 484–485
Boeve  et al. Journal of Geriatr Psychiatry Neurol 2004; 17:146-157
Aurora RN  et al. Journal of Clinical Sleep Medicine 2010; 6(1):85-95. Aurora RN  et al. Journal of Clinical Sleep Medicine 2010; 6(4):398-401.
https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001811/

Notes
Further reading
Siegel, Ronald (1992). Fire in the Brain: Clinical Tales of Hallucination. Warren, Jeff (2007). The Head Trip: Adventures on the Wheel of Consciousness. ISBN 978-0-679-31408-0. == External links ==
Whilst misdiagnosis of functional symptoms does occur, in neurology, for example, this appears to occur no more frequently than of other neurological or psychiatric syndromes. However, in order to be quantified, misdiagnosis has to be recognized as such, which can be problematic in such a challenging field as medicine. A common trend is to see functional symptoms and syndromes such as fibromyalgia, irritable bowel syndrome and functional neurological symptoms such as functional weakness as symptoms in which both biological and psychological factors are relevant, without one necessarily being dominant. Weakness
Functional weakness is weakness of an arm or leg without evidence of damage or a disease of the nervous system. Patients with functional weakness experience symptoms of limb weakness which can be disabling and frightening such as problems walking or a heaviness down one side, dropping things or a feeling that a limb just doesnt feel normal or part of them. Functional weakness may also be described as functional neurological symptom disorder (FNsD), Functional Neurological Disorder (FND) or functional neurological symptoms. If the symptoms are caused by a psychological trigger, it may be diagnosed as dissociative motor disorder or conversion disorder (CD). To the patient and the doctor it often looks as if there has been a stroke or have symptoms of multiple sclerosis. However, unlike these conditions, with functional weakness there is no permanent damage to the nervous system which means that it can get better or even go away completely.