If you are feeling a bit bleak or fragile at the moment, Cracked Up: The Darrell Hammond Story, may not be the thing to watch. It's one of those behind-the-grins documentaries about a comedian that is not particularly funny. The emphasis here is on the darker side of Hammond's life. There is some redemption – and a few laughs – but it is some time in coming.

Hammond is not particularly famous in the UK but in America he was a long-time lynchpin of the Saturday Night Live team, best known for his spot-on impressions. In the 1990s he often opened the show in the guise of President Bill Clinton. In footage of them having a chuckle together at public events they certainly sound alike, even if side by side he is a little shorter. 

But beyond the laughs there is considerable tragedy and trauma. Hammond had been brutally abused by his mother when he was a child and the fallout has unsurprisingly damaged him. The scars aren't just mental, they are physical. At one point when he was on SNL he was self-harming - in one old sketch shown here you can clearly see the knife marks up and down his arm.

It is not difficult to see the cause of his troubles in director Michelle Esrick's film. One illuminating anecdote recalls how when SNL was doing a Mother's Day routine, other performers invited their mothers along. Hammond didn't so the idea was that he would dress as his mother. This proved to be a monumental mistake, immediately unearthing painful memories.

In comedy you get people who are "on" all the time and those that are only on when the cameras start rolling. Hammond was one of the latter. In fact it seems he was so unlike his screen persona it was hard to believe they were the same person. He seems to come alive onscreen. 

This harrowing, brutally homest profile juxtaposes Hammond's history with him preparing for a solo show all about his life based on his book God, If You're Not Up There, I'm F*cked. It's a difficult monologue for him to do and we see him fighting back the tears sometimes and struggling to speak. But hopefully it is a cathartic experience for him.

Cracked Up is a tough watch at times - a documentary about comedy combined with a misery memoir. At the end it looks as if maybe Hammond is finally winning his battle against his demons and coming out of the other side. But it has clearly been a long, hard journey. 

Cracked Up: The Darrell Hammond Story is on Netflix now.