5 Month Old Daughter Waking at Odd Hours

The first thing I'm thinking is teething might be kicking in and making it hard for her to sleep. I would check that out. As far as letting her know it is not time to be awake, don't turn on lights or engage with her other than to feed and change her then time to go back to sleep. This of course takes patience unless you want to try letting her cry it out. I didn't like letting my little ones cry it out, so I would just keep patting them and singing their favorite lullaby until they fell asleep again. This will pass over time :)

No great advice, but my almost 5 month old is totally doing the same thing. :)

My son did the same thing at 5.5 months and I've since read many letters at this site with similar stories about sleep patterns at this age.
My solution, which worked beautifully for us, was to employ the sleep training methods from Dr. Marc Weissbluth's "Healthy Sleep Habits, Happy Child". This is a "cry it out" method, which I understand is not for everybody. I didn't think it'd be for me either, but after 3 nights my son was pretty much in a schedule. The book is written by a sleep expert/pediatrician and based on sound science and research.
There's something about that 5 month mark!

No advice either- just that my 3 /2 month old is doing the same.

He went from sleeping 9PM-5AM to now up at odd hours. He is starting to wake up at 230 and 530 AM.. not sure why!