Conclusion
Five to eight consecutive nights of PSD, with preserved SWS, increased CSF orexin but had no effect on CSF biomarkers for amyloid deposition, neuronal injury, and astroglial activation.
Methods
A randomized, cross-over study conducted at the University of Gothenburg. The participants (N = 13) were healthy adults (20-40 years of age) with a normal sleeping pattern. The participants underwent a baseline sleep period consisting of five nights with 8 hr spent in bed. A subsequent period with PSD consisted of five nights of maximum 4 hr of sleep per night. Four participants were also subjected to a prolonged period of PSD consisting of eight nights with 4 hr of sleep per night. Sleep was monitored by means of observation, actigraphy, and continuous polysomnographic recordings. CSF samples were collected by routine lumbar puncture after each period. CSF biomarkers included the 38, 40, and 42 amino acid-long Aβ isoforms, total-τ, phospho-τ, orexin, monoamine metabolites (3-methoxy-4-hydroxyphenylglycol, homovanillinic acid, and 5-hydroxyindoleacetic acid), neuron-derived biomarkers (neurofilament light, neuron-specific enolase, and fatty acid-binding protein), and astro- and microglia-derived biomarkers (glial fibrillary acidic protein, S-100B, and YKL-40).
Results
PSD was associated with a 27 per cent increase in CSF orexin concentrations (p = 0.001). No PSD-related changes in CSF biomarkers for amyloid build-up in the brain, Alzheimer's disease (AD)-type neurodegeneration, or astroglial activation were observed. PSD led to a shortening of time spent in all sleep stages except slow-wave sleep (SWS).