If sleep got harder right when you thought it would get easier, there is a real reason for it. Around 4 months a baby's sleep changes for good reasons: their brain is growing up. It can mean more waking for a few weeks. This is a step forward, even when it does not feel like one.
Newborn sleep is chaotic by design. Around 4 months, babies start moving through sleep cycles more like adults do, which is why many wake more between cycles for a few weeks. It usually settles. It is a sign of growth.
Many babies this age begin sleeping one longer stretch at night, often 4 to 6 hours, with naps during the day. Every baby is different, and some, especially breastfed babies, still wake to feed. That is still within normal.
Back to sleep, every time. Firm flat surface, fitted sheet, nothing else in the space. As babies start to roll, keep placing them on their back to start, and keep the space bare.
Keep placing baby on their back for every sleep, on a firm flat surface with nothing else in it. Couches, armchairs, and adult beds are not safe for sleep. Call your pediatrician if baby is very hard to wake, will not feed, or seems unusually drowsy.
Around this age, solid food starts to come up as a question, even if you are not there yet. And if the broken sleep is wearing on you, checking in with yourself is always worth it.