Will a new mattress or pillow improve your sleep and back?

Short answer

For a mattress, yes; for a pillow, not for sleep. Among 313 people with back pain, pain improved more on a medium-firm mattress than on a firm one, and replacing beds that averaged 9.5 years old raised sleep scores. Pillow type did not change sleep quality; in people with neck pain, latex pillows only slightly reduced neck pain.

Will a new mattress or pillow improve your sleep and back?
'Firm mattress → straight back → less pain': is it true?
For a long time, people have said a sore back needs a firm mattress. Ads also promise that expensive pillows bring deep sleep. We checked mattress firmness, replacing an old bed, and pillows, in that order.
Is firmer better for the back?
No, pain improved more on medium-firm
313 people with back pain were randomly assigned to sleep for 90 days on a firm mattress (2.3 on a 10-step scale) or a medium-firm one (5.6). On medium-firm, the number of people whose pain in bed improved was 2.36 times higher, and those whose daily limitations improved was 2.10 times higher.
Compared with other materials, the same story
No result favored the firm mattress
141 people with back pain slept for a month on a waterbed, a foam mattress, or a firm mattress. The waterbed and foam groups did slightly better than the firm group on pain, daily function, and sleep, with no difference between the two. A review of 39 papers also found medium-firm ahead for comfort and sleep quality.
Does replacing an old bed improve sleep?
Sleep scores rose over 28 days after the switch
59 people slept 28 days in their own beds, which averaged 9.5 years old, and then 28 days in a new medium-firm bed, rating their sleep every morning (a before-and-after comparison with no separate comparison group). Sleep quality scores went up on the new bed and back discomfort went down. In a study of 62 people done the same way, back pain was highest with the cheapest beds.
What if it is too soft?
4 minutes to fall asleep, 7.7 on medium
12 people took 90-minute naps on a soft, a medium, and a firm mattress while their brain waves were measured. It took 12.42 minutes to fall asleep on the soft mattress and 7.71 minutes on the medium one. Sleep stages switched 29.17 times on the soft mattress, more than the 21.75 times on the firm one.
And pillows?
Pillow type did not change sleep quality
An analysis pooling 9 trials with 555 people with neck pain found that rubber (latex) pillows slightly reduced neck pain and morning pain. But sleep quality did not differ by pillow type. A review of 5 studies from 2015 to 2024 with 239 people also found no difference in sleep quality among latex, foam, and regular pillows.
Summary: change the mattress before the pillow
Medium-firm for the back; too soft delayed sleep
No result showed a firm mattress was better for a sore back, and pain improved more on medium-firm. A mattress that was too soft made falling asleep take longer. Replacing a bed used for close to 10 years raised sleep scores. Pillows did not change sleep quality, so choosing one that feels comfortable for the neck is enough.