I'm considering the usage of the thing after PoSI, and boy the Leveling guide's calculator is helpful.

Let's see. I assume the usage of the tincture of vigor.

=== Most efficient use (-3 CP Nightmares):

6 actions/echoes, -18 CP Nightmares, +6 CP Wounds.

3 actions/echoes for Wounds, total 9 actions/echoes.

-18 CP Nightmares drops lvl 7 to lvl 4, lvl 6 to lvl 2 (28 - 18 = 10, 21 - 18 = 3), lvl 5 to lvl 0 with 2 saved actions/echoes.

=== Comparable to the full vigor tincture (-2 CP Nightmares):

4 actions/echoes, -8 CP Nightmares, +4 CP Wounds.

2 actions/echoes for Wounds, total 6 actions/echoes.

-8 CP Nightmares drops lvl 7 to lvl 6 with extra -1 CP (lvl 5 on the verge of lvl 6), or lvl 4 to 2 CP nightmares (lvl 1 halfway to lvl 2).

=== Comparable to the half-full vigor tincture (-1 CP Nightmares):

21 actions/echoes, -21 CP Nightmares, +21 CP Wounds.

41 actions/echoes for Wounds, total 41 actions/echoes.

-21 CP Nightmares is a full lvl 6 dropped to 0.

=== Burning through two efficiency stages (-3 to -2 CP Nightmares)

10 actions/echoes, -26 CP Nightmares, + 10 CP Wounds.

5 actions/echoes for Wounds, total 15 actions/echoes.

-26 CP Nightmares drops lvl 7 to lvl 1 halfway to lvl 2, lvl 6 is annihilated.

A single way to reduce the habit (Time, the Healer does not, in fact, miraculously reduce your compulsion to take drugs in this game):

Is an 80% chance opportunity card.

Since the deck is always bloated, it's not guaranteed to appear every day. A few times in a week, perhaps.

Gives 3 extra uses for the bottle if you've already indulged it this many times or more.

I.e. + 3 CP Wounds, 4 actions, 3 choes for -9, -6, -3 CP Nightmares depending on the efficiency.

The only other storylet way of reducing Nightmares I know of is A Time In Bed, which eats your actions like crazy for an inefficient reduction with a hefty chance of backfire. The opportunity cards are few, too, and at least one uses a mid PoSI primary skill check iirc. Playing dream cards nullifies even that.

What's my conclusion? Well, I haven't visited a single menace location. Perhaps an occasional bout of madness is not, in fact, so bad, and thus the whole menace is less menacing. But still, the way I see it the laudanum is the stockpile option which you burn through, waste many actions by both indulging in drugs and counteracting wounds, all to get rid of a hefty chunk of nightmares with an indeterminate habit cooldown relying on drawing the right opportunity card. You can also take things slower, too - it's just at one point this storylet becomes prohibitively expensive till recovery. Not as bad as it seems, still not great since I see no other options. I'll have to limit my watchful challenges because of that...