Did you know that strokes follow predictable time-of-day patterns? They happen more often in the morning hours and are often more severe near the end of the sleep period. A study published in the Journal of Clinical Investigation, led by Lauren Hablitz PhD at the University of Rochester Medicine and building on more than a decade of research by Maiken Nedergaard MD DMSc (whose lab discovered the glymphatic system in 2012), found that reinforcing the body’s natural daily rhythms after stroke improved motor recovery, shrank lesion size, lowered brain inflammation and boosted the brain’s waste-clearing system in mouse models. The benefits appeared even when treatment started three days after the stroke, well beyond the window for clot-busting drugs.
The glymphatic system circulates cerebrospinal fluid through brain tissue, clearing waste products and the inflammatory signals that build up after injury. This clearance is most active during sleep and controlled by the body’s internal 24-hour clock; stroke disrupts both, which slows the cleaning down when the brain needs it most. As Hablitz puts it: ‘stroke is not just a vascular event, but a disorder of timing.’ Her theory is that much of the lingering damage after stroke comes down to a failure of clearance: ‘if the system responsible for clearing signalling molecules isn’t working properly, everything builds up.’
The researchers tested four ways of restoring circadian rhythm: timed light exposure, melatonin, a clock-targeting drug called KL001, and time-restricted feeding (eating within a set daily window). KL001 and time-restricted feeding were then tested in stroke models, and both improved recovery, reduced lesion size and lowered inflammation. ‘All of the cytokines moved in the same direction,’ Hablitz notes… the brain appeared to be clearing inflammatory signals across the board rather than the treatment hitting one single target. Time-restricted feeding is already under study for heart disease and diabetes; it needs no specialist equipment and could, in principle, be done at home.
This is still animal research and human trials are needed before anyone can say it works the same way in people. Hablitz’s next steps are to establish whether improved glymphatic flow directly drives recovery and whether circadian-based interventions can move into clinical trials. At ARNI, the ARNI Instructors and I treat sleep and daily rhythm as rehabilitation factors rather than background lifestyle advice; this research sets out a neurological mechanism behind that.
