Dr. Richard Horner's sleep research at University of Toronto spans over three decades, beginning with PhD work in one of the UK's first sleep labs. After postdocs at U of T and the University of Pennsylvania, he returned to Toronto in 1997 focused on developing tools to study actual sleep rather than just sleep-like behavior.

Horner's lab identified two critical mechanisms behind sleep apnea. In 2006, they discovered noradrenaline activates tongue muscles during wakefulness but drops during REM sleep, causing muscle tone loss. A 2013 breakthrough revealed muscarinic receptors suppress tongue movement during REM sleep. Blocking these receptors strongly activated the muscle, mapping the neural circuits that cause breathing disruptions.

These discoveries directly enabled Boston researchers to develop AD109, a daily oral medication combining a noradrenaline booster with a muscarinic receptor blocker. A phase 3 randomized clinical trial showed participants had four fewer breathing events per hour compared to placebo, with reduced airway obstruction and higher oxygen levels.

Currently, continuous positive airway pressure therapy remains the standard treatment, but many patients abandon it due to discomfort. If approved, AD109 could offer a viable alternative for the millions who struggle with CPAP devices each night.