The Effects of Daytime Psilocybin Administration on Sleep: Implications for Antidepressant Action.

Serotonergic agonist psilocybin is a psychedelic with antidepressant potential. Sleep may interact with psilocybin's antidepressant properties like other antidepressant drugs via induction of neuroplasticity. The main aim of the study was to evaluate the effect of psilocybin on sleep architecture on the night after psilocybin administration. Regarding the potential antidepressant properties, we hypothesized that psilocybin, similar to other classical antidepressants, would reduce rapid eye movement (REM) sleep and prolong REM sleep latency. Moreover, we also hypothesized that psilocybin would promote slow-wave activity (SWA) expression in the first sleep cycle, a marker of sleep-related neuroplasticity. Twenty healthy volunteers (10 women, age 28-53) underwent two drug administration sessions, psilocybin or placebo, in a randomized, double-blinded design. Changes in sleep macrostructure, SWA during the first sleep cycle, whole night EEG spectral power across frequencies in non-rapid eye movement (NREM) and REM sleep, and changes in subjective sleep measures were analyzed. The results revealed prolonged REM sleep latency after psilocybin administration and a trend toward a decrease in overall REM sleep duration. No changes in NREM sleep were observed. Psilocybin did not affect EEG power spectra in NREM or REM sleep when examined across the whole night. However, psilocybin suppressed SWA in the first sleep cycle. No evidence was found for sleep-related neuroplasticity, however, a different dosage, timing, effect on homeostatic regulation of sleep, or other mechanisms related to antidepressant effects may play a role. Overall, this study suggests that potential antidepressant properties of psilocybin might be related to changes in sleep.

Sleep, hippocampal volume, and cognition in adults over 90 years old.

BACKGROUND: Several lines of research support associations between sleep and cognition in older adults. However, there is a paucity of data regarding sleep and cognition in nonagenarians and centenarians. AIMS: The current study examined self-reported sleep quantity and sleep quality in relation to hippocampal volume and cognition in adults aged 90 and older. METHODS: A total of 144 participants of The 90+ Study completed The Medical Outcomes Study sleep questionnaire. Participants reported subjective sleep duration in hours and three sleep quality factors: sleep problems, adequacy, and somnolence. Neuropsychological assessments of memory, global cognition, language, and executive function were completed, on average, 61 days from the questionnaire. Hippocampal volume on 3 T MRI, adjusted for intracranial volume, was obtained in 82 participants. We performed multiple linear regressions, controlling for age, sex, education, sleep medication, and depression, to examine sleep characteristics in relation to hippocampal volume and cognitive performance in all the subjects and then stratified by cognition. RESULTS: Sleep duration > 8 h was associated with lower scores in tests of global cognition, memory, and executive function compared to sleep duration of 7-8 h when collapsing across cognitive status, but only with memory in cognitively impaired subjects, and not in cognitively normal subjects. CONCLUSIONS AND DISCUSSION: Long-sleep duration is associated with poorer global cognition, memory, and executive function in the oldest-old, and is only associated with memory in cognitively impaired oldest-old. Additional research is necessary to determine if sleep duration is a risk factor or a result of poor cognition in advanced age.