I started on 1mg and was slowly titrated up over several months. No effect at all until i got to 4mg, then noticed a gradual reduction in the frequency and intensity of nightmares and nighttime hypervigilance as the dosage increased.

My magic number seems to be 10mg. Nightmares greatly reduced, sleep up to 7hrs unbroken most nights (i was surviving on 4-5hrs broken sleep), and nighttime hypervigilance has eased some too. And the only negative side-effect is some slight dizziness if I stand up too quickly.

Have stayed at 10mg for around three months now and it continues to work well. And not just in terms of better sleep, I'm also having having less of what my team call day-nightmares. Could probably go to a higher dosage (and may over the holidays as they're a major trigger), but haven't wanted to risk increased side-effects.

In terms of lowering your blood pressure, that is something to watch out for. My blood pressure has always been high so Prazosin has actually been really helpful in that respect - I'm now sitting at the top end of the normal range instead of way over it. But for anyone whose BP is usually normal, or low, it would need to be monitored closely.

I do still have times when badly triggered that the nights become terrifying and sleepless again, but it tends to settle down after a few days now, rather than dragging on for weeks or months like it used to.

Fingers crossed you find a dosage that works for you.