robitussin

Each 5 mL of Robitussin DAC contains 10 mg of codeine, 100 mg of guaifenesin, and 30 mg of pseudoephedrine. ... Robitussin AC has a 3.5% alcohol content, and the versions with promethazine have 7% alcohol. Generic forms are available under the names Cheratussin DAC and Cheratussin AC.

Alcohol works on Gaba in almost the same way Benzos do.  It should be avoided at all costs.

There is nothing in Robitussin that would help with sleep except the Alcohol.  In my opinion, I would find something else.