I've chewed open and chased 350 mg worth of unisom soft gels at one time .  It made my feel lethargic , at some points a little confused , slurred and difficult speech and ridiculous dry mouth.  These side affects lasted to some degree from 9-12 hours.  At no point was I in fear for my life .  I do believe at double that dose I'd probably trip out and perhaps be fearful or dangerously confused . I also believe the physical effects at double that could also be scary and dangerous .   In the future I plan on only taking 150-200 mg at once max-