Feeding sets the clock
Light tells a body it's daytime. So does food. Feeding at roughly the same times is one of the signals that sets your baby's internal clock, and it doesn't have to be to the minute. It tells the brain when to be awake, when to digest, and when to start heading towards sleep.
Predictable meals reinforce the 24-hour cycle. The body learns to anticipate food and handle it efficiently. And hunger stops arriving at unpredictable hours, which is what drives a good deal of night waking.
Enough in the day
A baby who hasn't had enough during the day wakes more, because the body is asking for fuel.
Enough calories through the day means fewer wakings from hunger, and a baby who is satisfied at bedtime is less likely to wake genuinely hungry. That is the best-supported thing anyone can tell you about feeding and sleep, and it is most of what there is to say.
So if your baby is waking a lot, the instinct is often to offer less in the day so they take more at night.
It is usually the opposite of what people expect, and I'd say that catches most families out. Babies take more of their calories in daylight as they mature, and I'd expect longer stretches to follow that rather than cause it.
Milk changes through the day
If you breastfeed, your milk composition changes throughout the day! Morning milk contains components like cortisol to promote alertness, while evening milk carries more melatonin, which is part of how the day's rhythm reaches your baby. It’s nature’s way of giving your baby the right tools for the time of day.
If you are feeding pumped milk, labeling it with the time it was expressed and offering it at a similar time of day keeps that rhythm intact.
The daily rhythm in breast milk is one of the ways a body tunes itself to a baby's needs. I find it one of the more remarkable things in this whole subject.
What a feed does besides feed
Feeding is calming, for your baby and often for you too.
A feed also builds the security that sleep confidence rests on, and it helps the gut relax, which takes away some of the discomfort that gets in the way of settling.
Skin-to-skin contact and a calm cuddle during or after a feed do the same work. The contact is doing as much as the milk.
Those sleepy, content snuggles after a feed are doing real work. I'd call them part of how a baby settles rather than just a nice moment.
How you feed
How you feed matters as much as what or when. Responsive feeding means watching for your baby's hunger and fullness cues rather than the clock, and it teaches them to read their own body's signals.
The loop is simple. They signal, you respond, and what they learn from that is that their needs get met. The security that builds is what lets them relax, and relaxing is where settled sleep starts.
Feeding to sleep is normal and comforting, and I'd say it isn't a habit you have to undo. Some babies gradually start taking the last stretch themselves and some keep feeding to sleep for a good while yet. Either way, every feed is building trust, and in time the self-regulation that settled sleep rests on.
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Regular feeding times send clear signals to a developing internal clock. I'd say that is why a loose rhythm helps digestion and sleep settle together rather than separately.