COMMENTS: A decline in D2 receptors is a major marker for an addiction process. They probably bounce back fairly quickly with sleep (a guess). Good reason to get proper sleep. Note that sleep deprivation is associated with overeating. May be related to lower D2 receptors.
Evidence That Sleep Deprivation Downregulates Dopamine D2R in Ventral Striatum in the Human Brain.
J Neurosci. 2012 May 9;32(19):6711-7. Volkow ND, Tomasi D, Wang GJ, Telang F, Fowler JS, Logan J, Benveniste H, Kim R, Thanos PK, Ferré S.
National Institute on Drug Abuse, Bethesda, Maryland 20892, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland 20892, Medical Department Brookhaven National Laboratory, Upton, New York 11973, and Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11794.
Dopamine D2 receptors are involved with wakefulness, but their role in the decreased alertness associated with sleep deprivation is unclear. We had shown that sleep deprivation reduced dopamine D2/D3 receptor availability (measured with PET and [(11)C]raclopride in controls) in striatum, but could not determine whether this reflected dopamine increases ([(11)C]raclopride competes with dopamine for D2/D3 receptor binding) or receptor downregulation. To clarify this, we compared the dopamine increases induced by methylphenidate (a drug that increases dopamine by blocking dopamine transporters) during sleep deprivation versus rested sleep, with the assumption that methylphenidate's effects would be greater if, indeed, dopamine release was increased during sleep deprivation. We scanned 20 controls with [(11)C]raclopride after rested sleep and after 1 night of sleep deprivation; both after placebo and after methylphenidate. We corroborated a decrease in D2/D3 receptor availability in the ventral striatum with sleep deprivation (compared with rested sleep) that was associated with reduced alertness and increased sleepiness. However, the dopamine increases induced by methylphenidate (measured as decreases in D2/D3 receptor availability compared with placebo) did not differ between rested sleep and sleep deprivation, and were associated with the increased alertness and reduced sleepiness when methylphenidate was administered after sleep deprivation. Similar findings were obtained by microdialysis in rodents subjected to 1 night of paradoxical sleep deprivation. These findings are consistent with a downregulation of D2/D3 receptors in ventral striatum with sleep deprivation that may contribute to the associated decreased wakefulness and also corroborate an enhancement of D2 receptor signaling in the arousing effects of methylphenidate in humans.