Sleep
Night lights, white noise machines, swaddles and crib mobiles — the things that help a baby go down and stay down.
Sleep gear works best in combination. A steady sound covers the household noises that wake a light sleeper. A dim light lets you do a two in the morning check without switching on the overhead. A swaddle keeps a newborn's startle reflex from waking them in the first weeks. None of it is magic on its own; together it stacks the odds.
The lights here are warm and dimmable rather than bright and blue, because blue light works against melatonin at exactly the hour you don't want it to. Projectors give a wound-up child something slow to look at instead of a screen.
Swaddling has safe-practice guidelines around hip positioning and when to stop — usually once a baby shows signs of rolling. Worth reading up on before you start.