Exp Brain Res (2008) 185:165–173 DOI 10.1007/s00221-007-1143-5 123 RESEARCH ARTICLE EVects of 24-h and 36-h sleep deprivation on human postural control and adaptation M. Patel · S. Gomez · S. Berg · P. Almbladh · J. Lindblad · H. Petersen · M. Magnusson · R. Johansson · P. A. Fransson Received: 1 May 2007 / Accepted: 13 September 2007 / Published online: 12 October 2007  Springer-Verlag 2007 Abstract This study investigated whether human postural stability and adaptation were aVected by sleep deprivation and the relationship between motor performance and sub- jective scores of sleepiness (visuo-anlogue sleepiness scores, VAS). Postural stability and subjective sleepiness were examined in 18 healthy subjects (mean age 23.8 years) following 24 and 36 h of continued wakefulness, ensured by portable EEG recordings, and compared to a control test where the assessments were made after a normal night of sleep. The responses were assessed using posturography with eyes open and closed, and vibratory proprioceptive stimulations were used to challenge postural control. Pos- tural control was signiWcantly aVected after 24 h of sleep deprivation both in anteroposterior and in lateral directions, but less so after 36 h. Subjective VAS scores showed poor correlation with indicators of postural control performance. The clearest evidence that sleep deprivation decreased pos- tural control was the reduction of adaptation. Also several near falls after 2–3 min during the posturographic tests showed that sleep deprivation might aVect stability through momentary lapses of attention. Access to vision, somewhat, but not entirely reduced the eVect of sleep deprivation. In conclusion, sleep deprivation can be a contributing factor to decreased postural control and falls. Keywords Postural control · Sleep deprivation · Adaptation · Subjective scores · Attention Introduction Chronic sleep restrictions are an endemic in modern society, with large fractions of the population reporting daily sleep below the recommended 8 h per night (National_Sleep_Foundation 2005). This problem is associ- ated with long working hours, commuting, and family responsibilities especially in occupations such as health- care, the military and industrial manufacturing where the potential for sleep-related accidents is also high (Balkin et al. 2004). The frequency of this problem was highlighted in a survey by the National Sleep Foundation in 2005, showing that 60% of drivers in the United States admit to driving while feeling drowsy (National_Sleep_Foundation 2005). Horne and Reyner estimated that 20% of serious motorway collisions in the United Kingdom were due to sleepiness on the basis of surveys from police oYcers and police collision reports (Horne and Reyner 1995). Sleep deprivation may produce eVects normally associated with drunkenness such as a lack of coordination, judgment and reaction time (Williamson and Feyer 2000; Wilson et al. 2006). The similarities between tiredness and drunkenness have been evidenced in driving simulation studies. Wil- liamson and Feyer (2000) found that people who drove after being awake for 17–19 h performed worse than those with a blood alcohol level of 0.05%, which is the legal limit for driving in most western European countries. Although M. Patel · S. Berg · P. Almbladh · J. Lindblad · M. Magnusson · R. Johansson · P. A. Fransson (&) Department of Otorhinolaryngology Head and Neck surgery, Clinical Sciences, Lund, Lund University, 221-85 Lund, Sweden e-mail: Per-Anders.Fransson@med.lu.se S. Gomez Faculty of Applied Sciences, University of the West of England, Bristol BS16 1QY, Great Britain H. Petersen Department of Otorhinolaryngology Head and Neck surgery, University of Iceland, Landspitali University Hospital, Reykjavik, Iceland