To sign tired, extend your fingers while holding them together in each bent hand. Start with your fingers touching either side of your chest, with your elbows up. Then drop your elbows and shoulders, and stoop your back a little as your curved, open palms also twist downward while still touching the sides of your chest.
It is as if you are so tired you cannot keep holding your arms up.
The tired baby sign gives your baby a way to tell you when they need to take a nap without getting fussy.
Remember when teaching the tired sign to really feel and project tiredness. Make a little yawn while making the sign for added effect. The more dramatic you can make signs, the more memorable they are going to be.