Getting a PhD is no easy feat. So many gruelling hours and sleepless nights are required to obtain it. For one French woman, it took 30 years.

At the age of 91, Colette Bourlier has become one of the oldest people in France to be awarded a doctorate.

She wrote all 400 pages of her thesis by hand and received “high distinction” for her work that got her a doctorate in geography at the Université de Franche-comté in Besançon, eastern France.

ChangSha Night Net

But why did it take Bourlier 30 years to complete her PhD?

Apparently, she took a lot of breaks.

WATCH: Bruce Springsteen invites 88-year-old woman on stage during Toronto concert

Nonetheless, she successfully defended her thesis in front a jury for two hours on Tuesday. Since Bourlier is going deaf, she had to sit very close to the jury so she could hear their questions.

Her thesis examined the integration of migrants, especially women who had come to France from Algeria, Italy and Portugal in the 1970s, relevant today as Europe tries to grabble with a migrant crisis.

Her research ties in with her experience as a former geography and history teacher.

She began her PhD after she retired in 1983. Usually, it takes about three years for someone to complete their doctorate in France. But for the 91-year-old, it took a whole three decades.

But Bourlier isn’t the oldest person in the world to receive their PhD.

A 102-year-old German woman named Ingeborg Rapoport was awarded a doctorate last June, nearly 80 years after the Nazis prevented her from sitting her final exam.