Sleep extension improves neurocognitive functions in chronically sleep-deprived obese individuals.
BACKGROUND
Sleep deprivation and obesity, are associated with neurocognitive impairments. Effects of sleep deprivation and obesity on cognition are unknown, and the cognitive long-term effects of improvement of sleep have not been prospectively assessed in short sleeping, obese individuals.


OBJECTIVE
To characterize neurocognitive functions and assess its reversibility.


METHODS
Prospective cohort study.


METHODS
Tertiary Referral Research Clinical Center.


METHODS
A cohort of 121 short-sleeping (<6.5 h/night) obese (BMI 30-55 kg/m(2)) men and pre-menopausal women.


METHODS
Sleep extension (468±88 days) with life-style modifications.


METHODS
Neurocognitive functions, sleep quality and sleep duration.


RESULTS
At baseline, 44% of the individuals had an impaired global deficit score (t-score 0-39). Impaired global deficit score was associated with worse subjective sleep quality (p = 0.02), and lower urinary dopamine levels (p = 0.001). Memory was impaired in 33%; attention in 35%; motor skills in 42%; and executive function in 51% of individuals. At the final evaluation (N = 74), subjective sleep quality improved by 24% (p<0.001), self-reported sleep duration increased by 11% by questionnaires (p<0.001) and by 4% by diaries (p = 0.04), and daytime sleepiness tended to improve (p = 0.10). Global cognitive function and attention improved by 7% and 10%, respectively (both p = 0.001), and memory and executive functions tended to improve (p = 0.07 and p = 0.06). Serum cortisol increased by 17% (p = 0.02). In a multivariate mixed model, subjective sleep quality and sleep efficiency, urinary free cortisol and dopamine and plasma total ghrelin accounted for 1/5 of the variability in global cognitive function.


CONCLUSIONS
Drop-out rate.


CONCLUSIONS
Chronically sleep-deprived obese individuals exhibit substantial neurocognitive deficits that are partially reversible upon improvement of sleep in a non-pharmacological way. These findings have clinical implications for large segments of the US population.


BACKGROUND
www.ClinicalTrials.gov NCT00261898. NIDDK protocol 06-DK-0036.
Clinical Center, NIH, Bethesda, Maryland, United States of America ; Laboratory for Neurophysiology, Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands.
Eliane A
EA
Lucassen
Obesity Research Center, Endocrinology Unit, University Hospital of Pisa, Pisa, Italy.
Paolo
P
Piaggi
Clinical Center, NIH, Bethesda, Maryland, United States of America ; Center for Neuroscience and Regenerative Medicine, Bethesda, Maryland, United States of America.
John
J
Dsurney
Section on Neuroendocrinology of Obesity, NIDDK, NIH, Bethesda, Maryland, United States of America.
Lilian
L
de Jonge
Intramural Research Program, NIDDK, NIH, Bethesda, Maryland, United States of America.
Xiong-ce
XC
Zhao
Section on Neuroendocrinology of Obesity, NIDDK, NIH, Bethesda, Maryland, United States of America.
Megan S
MS
Mattingly
Section on Neuroendocrinology of Obesity, NIDDK, NIH, Bethesda, Maryland, United States of America.
Angela
A
Ramer
Section on Neuroendocrinology of Obesity, NIDDK, NIH, Bethesda, Maryland, United States of America.
Janet
J
Gershengorn
Clinical Center, NIH, Bethesda, Maryland, United States of America ; Department of Laboratory Medicine, Clinical Center, NIH, Bethesda, Maryland, United States of America.
Gyorgy
G
Csako
Section on Neuroendocrinology of Obesity, NIDDK, NIH, Bethesda, Maryland, United States of America.
Giovanni
G
Cizza
D000293:Adolescent; D000328:Adult; D001521:Behavior Therapy; D003071:Cognition / Q000502:physiology*; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D009765:Obesity / Q000150:complications / Q000523:psychology*; D011446:Prospective Studies; D012890:Sleep / Q000502:physiology*; D012892:Sleep Deprivation / Q000150:complications / Q000523:psychology* / Q000628:therapy*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D055815:Young Adult