Sleep deprivation in chronic somatoform pain—effects on mood and pain regulation Volker Busch a, ⁎, Joachim Haas a , Tatjana Crönlein a , Christoph Pieh a , Peter Geisler a , Göran Hajak b , Peter Eichhammer a a Department of Psychiatry and Psychotherapy, University of Regensburg, Germany b Department of Psychiatry, Michelsberg Clinic, Bamberg, Germany abstract article info Article history: Received 8 February 2011 Received in revised form 9 July 2011 Accepted 11 July 2011 Keywords: Sleep deprivation Somatoform disorder Chronic pain Thresholds Sleepiness Mood states Sleep deprivation was found to exert complex effects on affective dimensions and modalities of pain perception both in healthy volunteers and patients with major depression. Considering multifaceted links between mood and pain regulation in patients with chronic somatoform pain, it is intriguing to study sleep deprivation effects for the first time in this group of patients. Twenty patients with a somatoform pain disorder according to ICD-10 diagnostic criteria were sleep-deprived for one night, followed by one recovery night. Clinical pain complaints (visual analog scale), detection- and pain thresholds (temperature and pressure) as well as mood states (Profile of Mood States) were assessed on the day prior to the experiment, on the day after sleep deprivation and on the day after recovery sleep. We found a discrepancy between significantly increased clinical pain complaints and unaltered experimental pain perception after sleep deprivation. Only the clinical pain complaints, but not the experimental pain thresholds were correlated with tiredness-associated symptoms. Total mood disturbances decreased and feelings of depression and anger improved significantly after sleep deprivation. However, these changes were not correlated with a change in clinical pain perception. We conclude that sleep deprivation may generally change the reagibility of the limbic system, but mood processing and pain processing may be affected in an opposite way reflecting neurobiological differences between emotional regulation and interoceptive pain processing. © 2011 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Somatoform pain is defined as the presence of (chronic) pain for which no adequate physical etiology can be found or the underlying somatic alteration is not sufficient to fully explain the clinical symptoms. Psychological factors are known to play a pivotal role in the onset, severity and maintenance of chronic pain (Aigner and Bach, 1999). In this context, emotional dysregulation is considered as a key factor (Waller and Scheidt, 2006), which is reflected on a neurobi- ological level by a close involvement of the so-called medial pain network (Apkarian et al., 2005). In detail, limbic structures, such as the anterior cingulate cortex and the amygdala, constitute the medial part of the pain network, primarily engaged in modulating the affective and motivational dimension of pain perception. Recent work suggests that hyperactivation of this medial network including the amygdala and the anterior/mid insula is linked to a hypoactivational state of prefrontal cortical areas. This finding seems to be characteristic for somatoform pain patients and may reflect a reduced top-down inhibitory control of limbic pain regulating systems (Gundel et al., 2008). Therefore, alterations in the medial part of the pain network should be accompanied by changes in pain perception, especially in patients suffering from chronic pain syndromes. Discovering an efficient way of modulating the medial pain network may offer a successful way for treating chronic somatoform pain syndromes since conventional pharmaceutical strategies often fail (Rosenquist, 1997). Sleep deprivation (SD), defined as a complete lack of sleep during a prolonged period of time or a shorter than optimal sleep time (Orzel-Gryglewska, 2010), is known to modulate both affective processing and pain perception. Functional neurobiological investigations suggest that SD-induced activity changes in limbic circuits (Yoo et al., 2007), encompassing the medial pain network, may be responsible for these effects. With regard to pain processing, studies in healthy volunteers demonstrate ambiguous results concerning SD effects on pain percep- tion with no changes of thermal or pressure thresholds following SD (Drewes et al., 1997; Arima et al., 2001) or lowered pain thresholds even after three consecutive nights of sleep loss (Lentz et al., 1999; Onen et al., 2001). A recent study showed an increase of heat pain vulnerability in patients with depression following one or two nights of SD, though mood improved significantly during the intervention (Kundermann et al., 2008). The effect of sleep deprivation on patients suffering from Psychiatry Research 195 (2012) 134–143 ⁎ Corresponding author at: Center for Pain and Affective Disorders, Department of Psychiatry and Psychotherapy, University of Regensburg, Universitätsstraße 84, 93059 Regensburg, Germany. Tel.: + 49 941 941 0. E-mail address: Volker.busch@medbo.de (V. Busch). 0165-1781/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2011.07.021 Contents lists available at ScienceDirect Psychiatry Research journal homepage: www.elsevier.com/locate/psychres