As described in the fantastic book "Sweet Sleep" (published by LLLI and written by Diane Wiessinger, Diana West, Linda J. Smith and Teresa Pitman), researchers are questioning the idea that humans must sleep 8 hours straight every night.
In LLL meetings, we frequently talk about how it's totally normal not to expect a baby to sleep through the night. Babies have tiny tummies to fill, and a constant/biological survival need for warmth, protection, love and nourishment. Many moms report feeling more rested by going with the need, rather than fighting it. Breastfeeding and bedsharing make going with these needs easier for everyone. The book Sweet Sleep discusses many ways to get more rest at night while also nourishing your baby. The information in this wonderful book discusses breastfeeding, how to bedshare safely and enjoyably, and also other practical ideas for families that do not bedshare.
But, it's interesting also to note - according to both Sweet Sleep and this article "Try a Bi-Modal Sleeping Pattern If You Frequently Wake Up At Night", that it's completely normal for humans of any age to wake up during the night.
So, it seems that the phrase "burning the midnight oil" could be not one rooted from people over-doing it, but from the totally normal human activity of getting up during the night and using that time for all kinds of activities.
I particularly like this quote from the article "Of course, if you’re already sleeping well and feel rested during the day, there’s no reason to change your patterns. However, if you’re struggling to get the sleep you need, it may be worth considering if the stereotypical model works for you. If you frequently wake up during the middle of the night, getting up to do something rather than staring at the ceiling."
This way of thinking can be very relaxing - instead of thinking there's something wrong with your baby (or something wrong with you) if you wake up up at night, try thinking of it as totally normal. Get up and do something enjoyable. You may just fall back to sleep quickly, or you may just enjoy your nighttime activities. Either way, you will feel more rested having spent less time worrying about it - a win-win situation for sure!