Agreed. I have used this combination many times, mag citrate especially. Just taking a highly absorbable magnesium source like mag citrate by itself has amazed me in its ability to put the body/nervous system into a relaxed state.
And besides as a sleep aid, magnesium, imo is a must supplement as it supports and optimizes a great many biological functions. It is also a nutrient that is one of the most deficient in the avg American diet.