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Brain & Heart Sleep and limb vasodilation

in healthy normotensive subjects, hypertensive patients, Acknowledgments
and heart transplant recipients. Notably, heart transplant
recipients lack a circadian day/night – not wake/sleep None.
– hemodynamic alternation. 51,52 The mediation of this Funding
rhythm involves vasodilator stimuli traveling through the
spinal cord in a top-down fashion, and its absence is noted None.
when spinal fibers are interrupted. In patients with spinal
cord injury, devoid of top-down nervous regulation, no Conflict of interest
limb vascular rhythm is observed. According to anatomical The authors declare that they have no competing interests.
considerations, the leg circadian rhythm is absent in those
with lesions under T2 (paraplegic), while both leg and Author contributions
forearm circadian rhythms are lost in those with lesions Conceptualization: Edoardo Casiglia
over C6 (tetraplegic). Investigation: All authors
Recent advancements, such as magnetic resonance Methodology: All authors
imaging, have facilitated the measurement of limb flow Writing – original draft: All authors
(skin+subcutaneous+muscular) in humans. 64,65 However, Writing – review & editing: Edoardo Casiglia
this method is not suitable for continuous 24-h monitoring.
Therefore, venous-occlusion strain-gauge plethysmography Ethics approval and consent to participate
remains the optimal non-invasive method, and perhaps the Not applicable.
only one, for monitoring sleep-induced variations in limb
hemodynamics in subjects deliberately confined to bed. Consent for publication

5. Conclusion Not applicable.
The methodologies described here open new perspectives Availability of data
about the physiology of the peripheral arterial circle Data used in this work is available from the corresponding
by revealing significant limb vasodilation during sleep, author upon reasonable request.
except in patients with spinal cord injury. The evidence
that signals governing limb arterial flow and resistance References
rely on the integrity of the centripetal afferent nerve fibers
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Volume 2 Issue 1 (2024) 5 https://doi.org/10.36922/bh.1886