Justin Timberlake doesn't sing to his son.

Although the Grammy-award winner is one of the world's best known singers, his wife Jessica Biel revealed that she is on lullaby patrol for baby Silas because Justin doesn't want to bring his work home.

She told E! News: ''You know, it's hard when it's your business. You don't always bring it home and use that as your casual time. I sing to the baby, poor thing. I do a lot of 'Somewhere Over the Rainbow'.''

'Total Recall' star Jessica and husband Justin welcomed Silas Randall into the world in April this year and the actress loves seeing her little boy smile.

Asked what the best thing is, she gushed: ''Probably the moment he wakes up from a nap. He's sort of looking around and you sort of creep up and look over the crib and he looks up and he [sighs].

''Just a gummy mouth, no teeth, just a big smile, happy that you're alive and you're just looking at him. That's probably the most magical.

''[I get emotional] but you quickly move on from it because there is a dirty diaper in your palm.''