A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
psa 88:1Upon Mahalath--either an instrument, as a lute, to be used as an accompaniment (Leannoth, "for singing") or, as others think, an enigmatic title (see on Psa 5:1, Psa 22:1, and Psa 45:1, titles), denoting the subject--that is, "sickness or disease, for humbling," the idea of spiritual maladies being often represented by disease (compare Psa 6:5-6; Psa 22:14-15, &c.). On the other terms, see on Psa 42:1 and Psa 32:1. Heman and Ethan (see on Psa 89:1, title) were David's singers (Ch1 6:18, Ch1 6:33; Ch1 15:17), of the family of Kohath. If the persons alluded to (Kg1 4:31; Ch1 2:6), they were probably adopted into the tribe of Judah. Though called a song, which usually implies joy (Psa 83:1), both the style and matter of the Psalm are very despondent; yet the appeals to God evince faith, and we may suppose that the word "song" might be extended to such compositions. (Psa. 88:1-18)
Compare on the terms used, Psa 22:2; Psa 31:2.
psa 88:3grave--literally, "hell" (Psa 16:10), death in wide sense.
psa 88:4go . . . pit--of destruction (Psa 28:1).
as a man--literally, "a stout man," whose strength is utterly gone.
psa 88:5Free . . . dead--Cut off from God's care, as are the slain, who, falling under His wrath, are left, no longer sustained by His hand.
psa 88:6Similar figures for distress in Psa 63:9; Psa 69:3.
psa 88:7Compare Psa 38:2, on first, and Psa 42:7, on last clause.
psa 88:8Both cut off from sympathy and made hateful to friends (Psa 31:11).
psa 88:9Mine eye mourneth--literally, "decays," or fails, denoting exhaustion (Psa 6:7; Psa 31:9).
I . . . called-- (Psa 86:5, Psa 86:7).
stretched out--for help (Psa 44:20).
psa 88:10shall the dead--the remains of ghosts.
arise--literally, "rise up," that is, as dead persons.
psa 88:11amplify the foregoing, the whole purport (as Psa 6:5) being to contrast death and life as seasons for praising God.
psa 88:13prevent--meet--that is, he will diligently come before God for help (Psa 18:41).
psa 88:14On the terms (Psa 27:9; Psa 74:1; Psa 77:7).
psa 88:15from . . . youth up--all my life.
psa 88:16the extremes of anguish and despair are depicted.
psa 88:18into darkness--Better omit "into"--"mine acquaintances (are) darkness," the gloom of death, &c. (Job 17:13-14).