Should you, or should you not, ever wake a sleeping baby?
For the first few days, before babies are in a ‘fed’ state, they tend towards hibernation. They sleep to conserve energy, so they don’t wake up, so they don’t eat, so they don’t have energy, so they sleep to conserve energy. This is a bad cycle.
For breastfeeding babies, there is generally not a lot of milk available for a few days, until the milk “comes in.” Milk comes in two stages. The first milk is called colostrum. People tend to notice colostrum being produced starting somewhere in the second trimester — lactogenesis I. This milk is thick, yellow, and packed with antibodies, but there’s generally not a lot of it. For the first few days, baby nurses to get what colostrum they can, but also to stimulate the breasts. Within a few days, lactogenesis II happens, with the transition from colostrum to mature milk. Mature milk is milkier, more white than yellow, and there’s way more of it. Generally the day that milk “comes in” people feel very full — engorged. It can be hard for a baby to latch at that point, because the breast is more like a bowling ball, but once they get drinking that milk, they tend to stop losing weight, start gaining weight, start being more satisfied after feeding, and start sleeping more.
Babies are designed to lose a certain amount of weight. We generally ‘allow’ for 10% weight loss from their birth weight. Ideally milk comes in before the baby has lost too much weight. If the baby is losing weight quickly, or if milk is delayed in coming in, or both, then there can be a gap that needs to be filled either with someone else’s breastmilk or with formula.
If a baby is very jaundiced, feeding can be even more difficult. Jaundiced appearance comes from elevated levels of bilirubin. After a baby is born, they start breaking down their fetal red blood cells and replacing them with ‘adult’ red blood cells. Bilirubin is a product of this breakdown of red blood cells.
High levels of bilirubin make a baby very sleepy. I call this bili drunk — it’s the baby who sucks a few times and falls back asleep without really getting a proper feed. The way to get rid of bilirubin is to excrete it into the gut, where it binds to stool, and gets pooped out. But if baby is not eating, then there’s no stool to bind to, and the bilirubin gets reabsorbed. Making baby sleepy. And not eating.
Almost all babies are jaundiced to some degree. Babies are ‘allowed’ to have more bilirubin the older they are. There’s a graph called a nomogram that shows this hour-by-hour.
Some babies are at higher risk of hyperbilirubinemia (too much bilirubin). These include babies who are not feeding well (because they don’t poop out the bilirubin), babies who have a large collection of blood in a cephalhematoma (a big pocket of bruise on the scalp, usually from a vacuum delivery — all this blood needs to get broken down, resulting in more circulating bilirubin), or babies who have a blood type incompatibility (because red blood cells are being destroyed by misguided antibodies).
Some babies are at higher risk of having neurologic damage from the high levels of bilirubin. These include babies who are sick. Brain damage from high levels of bilirubin is called kernicterus.
Depending on the level, the risk of going higher, and the risk of damage from being high, the baby’s doctor can make a decision about when to retest and whether or not they need supplementation, home phototherapy, or to be admitted to the hospital for phototherapy.
Once babies are in a fed state and have some reserves, we can trust that when they hungry, they’ll wake up and let us know. Those babies we can let sleep. Generally babies will have one longer stretch of sleep — 3 hours, expanding to 4 or 5 hours as they get a little older and better fed — and wake up 8-10 times throughout the rest of the 24 hours to eat.
If baby is not waking on his own, not waking enough times, or not staying awake long enough to have a proper feeding, that is a problem.
Think of it like letting your baby set his own schedule. You supervise. If he’s not responsible in how he manages his schedule, then you take back some of that responsibility until he’s a little more mature and has a little more experience. It’s like parenting a teenager already!
tl;dr — baby needs to eat. If baby is waking herself to eat, you don’t need to wake her. If baby is not waking himself to eat, then you need to wake him. Regardless of the adage.