Ryan Reynolds and Blake Lively's baby is ''allergic to sleep''.

The couple, who tied the knot in 2012, welcomed their baby daughter into the world in December last year and Reynolds, 38, has revealed the family have hardly had any sleep ever since.

The Hollywood star - whose newborn child is reportedly called James - shared: ''It's exciting, nine weeks now! I do everything [for her].

''Our baby in particular is, we think, allergic to sleep.

''We joke that she ... thinks that she's keeping us [safe].

''She's protecting us from the sleep monsters. She's like, 'Oh, I gotta keep them up or the sleep monsters will get them.'''

Reynolds revealed he's tried different methods of getting his daughter to fall asleep - including using a line of multimedia toys for pre-school children - but admitted it often causes him to nod off rather than her.

He told 'The Tonight Show Starring Jimmy Fallon': ''The trick I try to use is that Baby Einstein stuff, but for me, that's like horse tranquilliser.

''No, really. I could go down on a lit stove. I could just fall [asleep]. Push me out an airplane, and I, yeah, and the weirdest dreams.''