The latest documentary feature from Ric Burns (The Civil War, American Experience) delves into the life and work of the acclaimed neurologist and writer, Oliver Sacks, and is a frank and utterly absorbing life-story, as told by Sacks, in the months leading up to his death in 2015.

Oliver Sacks: His Own Life has a slightly shaky start with the man himself making a joke about his profession to the film crew and an ensemble of close associates and friends, whilst the camera feels like it is trying to find somewhere to settle to launch the film proper.

One possible reason for this initial uncertainty could be the fact that the director was thrown unexpectedly into this most compelling of projects after he was approached by Kate Edgar, Sacks’ long-term book editor and friend, to film Sacks who had just two weeks earlier received a terminal cancer diagnosis and had only a few months left to live.

His medical condition coincided with the completion of his latest memoir, On the Move: A Life, which ends up providing a structure of sorts and the film soon relaxes into a chronological format with Sacks, narrator-in-chief, talking candidly about his life, work, and relationships. Sometimes he quotes directly from his own book, which gives the documentary an interesting dual authorial voice, his and that of the filmmakers. In other circumstances this process could feel too subjective or even a vanity-led project, but Sacks’ searing self-examination, in conjunction with his professional expertise, dampens any such criticism and a more candid and authentic documentary is hard to imagine.

In brutally honest terms Sacks recalls the times in his life where he says he failed spectacularly, and it is this deep reflection that goes to the heart of Burns’ film and what makes is such a mesmerising watch. The filmmakers weave personal details such as his mother’s visceral rejection of him when he told her he was gay, his drug taking, to becoming a champion weightlifter, into the research and work projects that he would later become renowned for.

Most famously, in the late 1960s Sacks’ study of post-encephalitic or “sleeping sickness” patients whose unusual conditions appeared in the 1920s and went on to reach epidemic proportions before disappearing entirely, highlighted how Dopa medication could bring physical movement and speech back to those who had been in catatonic or non-communicative states. The neurologist’s journey of discovery here is very well told as Sacks recounts the elation and then concern when the medication or the experience of this new state of being for some patients, began to throw-up negative side affects. This study and some of the patients and their conditions end up in his book, Awakenings, which was later adapted into a film starring Robin Williams and Robert DeNiro.

There is an abundance of source material from The Oliver Sacks Foundation, going back decades, ranging from stills, footage to meticulously kept notebooks detailing conditions, treatments, results, and setbacks. Some of the most interesting archive pertains to his work with the group of encephalitic patients. Whilst it is quite startling to view, it gives the audience a rare glimpse into how progressive Sacks’ research was at that time and how he pioneered an alternative approach to the doctor-patient dynamic which involved exploring in greater depth who the patient was, and for him as a clinician, to try and understand what it was like to be that other person.

His intellect and humanity are ever present and Burns delivers an impressive line-up of contributors to give testimony to those attributes drawn from the fields of science, psychology, and literature and include Christof Koch, Lawrence Weschler, Jonathan Miller and Paul Theroux, who stand shoulder to shoulder with people whose conditions Sacks examined such as autism with Temple Grandin and Tourette’s Syndrome with Shane Fistell.

After years of not being taken seriously by his peers, Sacks’ research caught the attention of eminent neuroscientists in the 80’s and 90’s and eventually the medical establishment started to acknowledge the importance of his work into the study of human consciousness or as Sacks describes it, the intersection between biology and biography. As he nears the end of his memoir on screen, the filmmakers illustrate the huge contribution he made to the field of mental health and raising awareness about the workings of the human mind. When Lawrence Weschler, Head of Columbia Hospital’s Neurology Department, explains that around 70% of his doctors in training who choose neurology, site Oliver Sacks as a huge influence, one can’t help reflecting that as far as legacies go, that probably takes some beating.

Sacks’ fascination with the uniqueness of being human pulses throughout, creating an unmissable portrait of a man, scientist, and writer, as painted by himself and those who knew and admired him, in vivid, brilliant colours.