Awakenings (1990)

In 1969, Dr. Malcolm Sayer is a physician working with catatonic patients who survived an encephalitis epidemic. He discovers certain stimuli can reach these patients and begins testing a new drug called L-Dopa. One patient, Leonard Lowe, fully awakens but experiences side effects and eventually returns to his catatonic state. Despite the temporary nature of the awakening, Sayer realizes that the patients have learned to appreciate and live life. The film ends with Sayer ready to continue his work with Leonard.