Learning how to self-settle and go to sleep is a skill babies usually
gain during the first year of life.
I found that taking my babies outside every day helped them sleep better. Fresh air can both soothe and stimulate. When we had a garden we would spend half an hour or more outside in a shady spot both morning and afternoon. If I was busy hanging the washing out or gardening I would place the baby in their pram. Many times they would fall asleep under a tree and I would put a net cover over the pram.
Hammocks, like the one pictured, only work when baby is very young and cannot roll or sit up. I always went for a walk with the baby in the stroller every day if we were living in an apartment and noticed that on stormy days or days when I did not get outside then sleep time was either less or baby was unsettled.
Establishing sleep rhythms means creating the conditions that help baby to let go and fall to sleep. Being calm ourselves, really helps baby to relax and let go of all the excitement of the day.