Yes! Getting enough sleep is the #1 productivity enhancer, IMHO. All of the other tips and techniques are smaller terms in the equation.
The insidious thing about sleep deprivation is that people can be measurably more stupid, yet feel like "oh I'm just a bit tired -- I'll have a coffee".
My performance actually deteriorates if I stay in bed past certain threshold (>9 hours). I think it's not the quantity, it's a whole host of things that need to be finely tuned.
The insidious thing about sleep deprivation is that people can be measurably more stupid, yet feel like "oh I'm just a bit tired -- I'll have a coffee".