Introduction: Sleep spindles are short burst-like waveform of signals generated in the electroencephalogram (EEG) recorded during sleep, and these are the electrical representation of an oscillatory neuronal activity of thalamic neurons. Some studies have linked different sleep spindle parameters with intelligence quotient (IQ). But there is a lack of uniformity in different studies, as spindle parameters may be positively associated with cognition variables in one study, but those same parameters might be negatively associated or even unrelated in other studies. The present study was conducted to further throw light on the correlation of sleep spindle activity with IQ. Objective: To find the association between different sleep spindle parameters and IQ. Method: The sleep spindle data of 50 healthy young medical students aged between 18 and 23 years were taken from previously conducted sleep studies (polysomnography), which were available in the sleep lab in the department of physiology (King George\'s Medical University). The participating students underwent a Wechsler IQ test. The result of the test was correlated with sleep spindle parameters available with us to see any correlation. Results and conclusion: Sleep spindle frequency was negatively correlated with the IQ, and the number of spindles in deep sleep (N3) was positively associated with the IQ of an individual.
Fernandez LMJ, Lüthi A. Sleep spindles: mechanisms and functions. Physiol Rev 2020;100(2):805–868. DOI: 10.1152/physrev.00042.2018.
Zeitlhofer J, Gruber G, Anderer P, et al. Topographic distribution of sleep spindles in young healthy subjects. J Sleep Res 1997;6(3):149–155. DOI: 10.1046/j.1365-2869.1997.00046.x.
DeGennaro L, Ferrara M. Sleep spindles: an overview. Sleep Med Rev 2003;7(5):423–440. DOI: 10.1053/smrv.2002.0252.
Schabus M, Dang-Vu TT, Albouy G, et al. Hemodynamic cerebral correlates of sleep spindles during human nonrapid eye movement sleep. Proc Natl Acad Sci USA 2007;104(32):13164–13169. DOI: 10. 1073/pnas.0703084104.
Peters KR, Ray L, Smith V, et al. Changes in the density of stage 2 sleep spindles following motor learning in young and older adults. J Sleep Res 2008;17:23–33. DOI: 10.1111/j.1365-2869.2008.00634.x.
Fogel SM, Smith CT. The function of the sleep spindle: a physiological index of intelligence and a mechanism for sleep-dependent memory consolidation. Neurosci Biobehav Rev 2011;35(5):1154–1165. DOI: 10.1016/j. neubiorev.2010.12.003.
Gaillard JM, Blois, R. Spindle density in sleep of normal subjects. Sleep 1981;4(4):385–391. DOI: 10.1093/sleep/4.4.385.
Nader RS, Smith CT. Correlations between adolescent processing speed and specific spindle frequencies. Front Hum Neurosci 2015;9:30. DOI: 10.3389/fnhum.2015.00030.
Steriade M. Grouping of brain rhythms in corticothalamic systems. Neuroscience 2006;137(4):1087–1106. DOI: 10.1016/j.neuroscience.2005.10.029.
Nader R, Smith C. A role for stage 2 sleep in memory processing. In: Maquet P, Smith C, Stickgold R, editors. Sleep and synaptic plasticity. Oxford: Oxford University Press; 2003. p. 87–98.
Fogel SM, Nader R, Cote KA, et al. Sleep spindles and learning potential. Behav Neurosci 2007;121(1):1–10. DOI: 10.1037/0735-7044. 121.1.1.
Fogel SM, Smith CT. Learning-dependent changes in sleep spindles and Stage 2 sleep. J Sleep Res 2006;15(3):250–255. DOI: 10.1111/j.1365-2869.2006.00522.x.
Schabus M, Hödlmoser K, Gruber G, et al. Sleep spindle-related activity in the human EEG and its relation to general cognitive and learning abilities. Eur J Neurosci 2006;23(7):1738–1746. DOI: 10.1111/j.1460-9568.2006.04694.x.
Buzsaki G. Two-stage model of memory trace formation: a role for “noisy” brain states. Neuroscience 1989;31(3):551–570. DOI: 10.1016/0306-4522(89)90423-5.
Rosanova M, Ulrich D. Pattern-specific associative long-term potentiation induced by a sleep spindle-related spike train. J Neurosci 2005;25(41):9398–9405. DOI: 10.1523/JNEUROSCI.2149-05.2005.
Genzel L, Kroes MC, Dresler M, et al. Light sleep versus slow wave sleep in memory consolidation: a question of global versus local processes? Trends Neurosci 2014;37(1):10–19. DOI: 10.1016/j.tins.2013.10.002.
Hoedlmoser K, Heib DPJ, Roell J, et al. Slow sleep spindle activity, declarative memory, and general cognitive abilities in children. Sleep 2014;37(9):1501–1512. DOI: 10.5665/sleep.4000.
Gruber R, Wise MS, Frenette S, et al. The association between sleep spindles and IQ in healthy school-age children. Int J Psychophysiol 2013;89(2):229–240. DOI: 10.1016/j.ijpsycho.2013.03.018.
Kurdziel L, Duclos K, Spencer RMC. Sleep spindles in midday naps enhance learning in preschool children. Proc Natl Acad Sci USA 2013;110(43):17267–17272. DOI: 10.1073/pnas.1306418110.
Cox R, van Driel J, de Boer M, et al. Slow oscillations during sleep coordinate interregional communication in cortical networks. J Neurosci 2014;34(50):16890–16901. DOI: 10.1523/jneurosci.1953-14.2014.
Lafortune M, Gagnon JF, Martin N, et al. Sleep spindles and rapid eye movement sleep as predictors of next morning cognitive performance in healthy middle-aged and older participants. J Sleep Res 2014;23(2):159–167. DOI: 10.1111/jsr.12108.
Geiger A, Huber R, Kurth S, et al. The sleep EEG as a marker of intellectual ability in school age children. Sleep 2011;34(2):181–189. DOI: 10.1097/wnr.0b013e32834e7e8f.
Tessier S, Lambert A, Chicoine M, et al. Intelligence measures and stage 2 sleep in typically-developing and autistic children. Int J Psychophysiol 2015;97(1):58–65. DOI: 10.1016/j.ijpsycho.2015.05.003.
Chatburn A, Coussens S, Lushington K, et al. Sleep spindle activity and cognitive performance in healthy children. Sleep 2013;36(2):237–243. DOI: 10.5665/sleep.2380.
Gibson ES, Powles ACP, Thabane L, et al. “Sleepiness” is serious in adolescence: two surveys of 3235 Canadian students. Pediatr North Am 2006;58:637–647. DOI: 10.1186/1471-2458-6-116.
Lo JC, Ong JL, Leong RLF, et al. Cognitive performance, sleepiness, and mood in partially sleep deprived adolescents: the need for sleep study. Sleep 2016;39(3):687–698. DOI: 10.5665/sleep.5552.
Mikoteit T, Brand S, Beck J, et al. Visually detected NREM Stage 2 sleep spindles in kindergarten children are associated with stress challenge and coping strategies. World J Biol Psychiatry 2012;13(4):259–268. DOI: 10.3109/15622975.2011.562241.
Mikoteit T, Brand S, Beck J, et al. Visually detected NREM Stage 2 sleep spindles in kindergarten children are associated with current and future emotional and behavioural characteristics. J Sleep Res 2013;22(2):129–136. DOI: 10.1111/j.1365-2869.2012.01058.x.
Hartman DE. Wechsler Adult Intelligence Scale IV (WAIS IV): return of the gold standard. Appl Neuropsychol 2009;16(1):85–87. DOI: 10.1080/09084280802644466.
Bright P, Hale E, Gooch VJ, et al. The National Adult Reading Test: restandardisation against the Wechsler Adult Intelligence Scale—Fourth edition. Neuropsychol Rehabil 2018;28(6):1019–1027. DOI: 10.1080/09602011.2016.1231121.