United Kingdom, April 1 -- Jack Black is having "nightmares" ahead of his return to 'Saturday Night Live'.

The 'Minecraft Movie' star last hosted the comedy sketch show almost 20 years ago and he admitted it feels "cray cray" to be returning to the programme after so long, but he's also looking forward to his guest stint on 5 April.

Asked how he is preparing for the show, Jack told Variety: "Just you know, having lots of nightmares and night terrors and also fond memories flooding back. It's crazy, very exciting."

The 55-year-old star - who also guest hosted 'SNL' in 2002 and 2003 - admitted he doesn't yet know what sketches he will be involved in and thinks that's what makes the role so exciting.

He said: "You know what they're think...