S.H.
Here is a link on how much sleep a baby needs:
http://www.babycenter.com/0_how-much-sleep-does-your-chil...
Unless you want her to be entrenched in her late sleep schedule... then that's fine. But what if, by some reason she has to get up earlier.. per your/Hubby's work schedule or later, when she starts school. And right now, she is having to change her sleep schedule, because you are going back to work.
Personally, I feel that's too late for a 5 month old to be going to bed... but that's just me. Nothing personal.
Next, it is NORMAL NORMAL NORMAL for your ONLY 5 month old baby to be waking that many times.**For the 1st year of life, a baby MUST be fed on-demand 24/7... this is per our Pediatrician. Next, during "growth-spurts" a baby NEEDS to be fed more, more often, and in larger quantities... because their body is growing. THIS is normal. If they do "not" get enough intake, they WILL be hungry, they WILL want to feed more to make up for inadequate intake, AND they will not sleep well and will cry. Some babies even "cluster feed" which means they even need to feed EVERY HOUR. THIS is also normal. Breastmilk/Formula is the PRIMARY source of nutrition for a baby's first year of life... NOT solids, NOT other liquids.
Next, a baby wakes. Your baby is only 5 months old. A baby does not sleep according to 'adult' expectations or standards. For a BABY... "sleeping through the night" means sleeping for at least 5-6 hours straight. BUT NOT all babies do this, much less this young. A baby wakes and it's normal. That's what babies do.
And once they do "seem" to get into a good sleep pattern.. it WILL change again, as they change and grow and change developmentally and hit milestones.
Next, a baby ALSO wakes because: teething, or, illness, or hunger, or discomfort, or separation anxiety, or developmental changes, or growth spurts- at this age and older.
"Wakings" will continue... throughout childhood.
Next, going until 5:00am, when you finally nurse her, to me, is a long time. She is waking up a lot, prior to that... and you should nurse her instead of waiting until 5:00am. The reason is: if and whenever a baby is going through growth-spurts or changes... they wake, because they need to feed. If you do not feed them... they will wake more, cry, be constantly hungry, and not be satisfied. It has been proven in numerous studies that feeding only according to a "schedule" results in a baby NOT getting adequate intake and not enough calories and not enough nutrition... and in extreme cases it affects their weight gain/growth/development and their bonding with their Mom.
Switching a baby's sleep schedule, suddenly, is not easy. For all her life, she has been used to sleeping at 8-9:00pm. You need to do it gradually... perhaps giving her 2 naps (which is NORMAL for this age), instead of 3 short ones. To me, 3 naps of ONLY 30-40 minutes is not a "nap" it is just a quick wink. By the time a baby gets into the "deep sleep" and REM cycles, then her nap is already over... if not even deep enough of a sleep.
Naps at this age is: wake in the morning at anywhere from 6:00am-7:am. Then, nap about 9:00am, for 2 hours. Then afternoon nap at about 2:00pm, for 2 hours. For example.
A baby, this age, typically gets tired about 2-3 hours AFTER waking.
I once baby-sat a baby, that regularly went to bed at night anywhere from 11:00pm onward... her parents said "this is when she gets tired and we're so busy & we're night-hawks too... " Fine. Then their baby would wake up for the day at like 12:00 in the afternoon. Fine. BUT... that meant their baby was not really developing well, was always tired, and they were ALWAYS late to appointments and meetings and the Doctor appointments, and even in dropping her off at my house. Their daughter is now about 5 years old... and from what I hear, their child STILL has a hard time keeping up with a regular schedule and they are always late in taking her to school... because they say their daughter just has her own "sleep schedule." Oh well.
Whatever sleep routine and schedule you start now and have kept up... keep in mind that it will affect the LONG TERM consequences and adaptability of a baby as she becomes a toddler, then a child. Because once sleep habits are entrenched... and the older they get, the harder it is to "transition" them to something else, per adult schedules. A child needs lots of time to switch schedules and get used to it. If you are going back to work in about a month or 2... then that's fine, you have time to 'transition' her to an earlier bedtime and nap schedule... BUT, if you are going back to work next week... then I would say no, that is not enough time. And your baby will not adjust in so short a time period.
Next, a baby will wake at night, sometimes many times, and it's okay. Breastmilk digests a LOT faster than say Formula... because of that, a baby gets hungrier and more often. ALSO, some babies have a bigger appetite than others... or a higher metabolism, so they need to feed more. Or, sometimes, there is not enough milk coming out, so a baby will wake more because they are NOT getting enough in their feedings, no matter how often. Make sure, your milk production IS sufficient.. and that she is latching on well.
Well sorry for rambling, just some ideas, all the
best,
Susan