Tylenol PM is fine. It's the same ingredient as Benadryl, which is also safe.
I'm not sure about Unisom.
Unisom is time released benedryl. The problem would be that you might fall asleep while nursing the baby which would be a risk for smothering (even if you're sitting up, it would put you at risk for tipping over and smothering...couch and chair sleeping with infants are much much more dangerous that safe bed sleeping), and/or not wake often enough to nurse the baby at night, putting you at risk for a diminishing milk supply.
I would instead recommend a homeopathic product called Calms Forte, made by Hylands, but still wouldn't use it if you cosleep. Calms Forte will help you get to sleep and stay asleep without drugging you.
Unisom is listed as an L4 (the least recommended drug level for lactating mothers). Dr. Hale's book reads:
"This is an antihistamine similar in structure to benadryl. Because it has strong sedative properties, it is primarily used in over the counter sleep aids. Like other such antihistamines, it should be used with caution in infants and PARTICULARLY in premature or term neonates (new borns) due to side effects such as central nervous system stimulation or even sedation. Levels in breastmilk are not known but caution is recommended particularly in infants with apnea or other respiratory syndromes"
Hale doesn't list MUCH as an L4, I'd stay away from it.
STraight Benedryl is listed as an L2, and says:
"Small but unreported levels are thought to be secreted into breastmilk although at present we do not have data on levels in breastmilk or the relative infant dose. However, the use of this sedating antihistimine in breastfeeding mothers is not ideal. Non-sedating antihistamines are generally preferred. There are anecdotal reports that diphendydramine suppresses milk production, however there are no data to support this."
Pedatric concerns are listed as: "None reported, but observe for sedation. Some suggestions of reduced milk supply."
Basically if you can get by without them, I think it's a good idea to avoid sleep aids.