Professor Williams graduated from University College Hospital, London and, after a lectureship at The Cardiothoracic Institute, Brompton Hospital, moved to Harvard where his interest in sleep began with the investigation of SIDS.
An invitation to UCLA allowed an early interest in OSA with the very first reports of OSA causing hypertension and of oximetry as a natural diagnostic tool. Home-built nasal CPAP was first used in 1981 and then nasal ventilation for the first time in 1988. In 1985 Dr Williams became tenured Professor of Medicine at UCLA and Co-Director of UCLA's sleep Laboratory.
As sleep Medicine gelled as a speciality, Prof Williams became an accredited polysomnographer and later member of the American Academy of Sleep Medicine and as such has mentored more than thirty trainees.
At St Thomas's Hospital, London, he has developed one of the UK's only comprehensive sleep services with continued interest in Sleep Disordered Breathing and its treatment, the first UK report of REM Behaviour Disorder, the first reports of the genetics of Phase Delay Syndrome, and the genetics of snoring and RLS in the St Thomas's Twin Cohort, along with unique explorations of the link between orexin and sleepiness and the setting of UK medico-legal case law (sleepwalking as a defence for drink driving).
Dr Williams is a Diplomat of the American Board of Sleep Medicine, a founding member of The British Sleep Foundation, the Sleep Medicine Section of the Royal Society of Medicine, and the RLS UK Group.