Sleep Number P-5 VS. I-8 – Which Mattress Is Right For You?

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Sleep Number’s popular P-5 model and their luxurious I-8 model both have a lot to offer customers. The P-5 could be the perfect balance of firmness and cushion and the I-8 may be just the bed to keep you cool and comfortable all night long.

So, which one is the best mattress for you? Check out our handy guide as we go over the details of each mattress and help you decide if one is right for you.

Compare all Sleep Number beds here

Key Similarities

  • Both models are pillow top mattresses
  • A variety of standard sizes – including FlexTop
  • Individual or dual air chamber options with DualAir™ adjustability

Both come with this optional feature:
FlexFit™ Adjustable Bases

Key Differences


  • 11” mattress profile
  • European style pillow top design that includes 2” of hypersoft quilting foam for a plush surface
  • 2” of proprietary PlushFit foam- supportive foam is designed exclusively for Sleep Number to naturally conform to the body’s curves
  • Mattress fabric is made with a rayon/polypropylene blend for smoothness and durability
  • 5 zones specifically designed to contour to the head/neck, shoulders, lower back, hips, and feet
  • $2,099.99 for a Queen


  • 13” mattress profile
  • Duvet pillow top that includes 2” of hypersoft quilting foam for a plush surface and Outlast temperature balancing technology to minimize temperature swings
  • 1” foam base pad underneath the air chamber(s)
  • 3” of proprietary PlushFit foam – supportive foam is designed exclusively for Sleep Number to naturally conform to the body’s curves
  • 7 zones specifically designed to contour to the head, shoulders, lower back, hips, knees, lower legs, and feet
  • Mattress fabric is made with a polyester/polypropylene blend fabric that is designed to be soft and breathable
  • Sleep IQ Technology included
  • $3,499.98 for a Queen

What I Found From Several Live Chat Sessions

After speaking with Sleep Number Customer Service representatives, I learned about a few extra details that may help people decide between a P-5 or an I-8 mattress.

  • Mattress Top: Both the P-5 and the I-8 mattresses are pillowtops. They also both have 2” of hypersoft quilting foam sewn into the mattress top. The biggest difference between the two is that the I-8 has temperature balancing fabric (Outlast Technology) woven into the mattress surface to help keep people cool.
  • Popularity: The P-5 model is Sleep Number’s most popular bed. The salesperson I spoke to at a Sleep Number store said it had a good balance between cushion and natural firmness from the air chambers.

Which Should People Pick?

P-5 if…

  • People Like a Balance of Firmness and Cushion. Almost every single Customer Service representative I talked to made sure to tell me that the P-5 model was the most popular and bestselling mattress. When I asked why, they frequently told me people liked the European style pillowtop design and the 2” layer of their proprietary PlushFit foam, which is designed to provide the perfect balance of support and pressure relief.
  • People Are On A Budget. There is a $1,400 price difference between Queen size P-5 and I-8 mattresses. Going with the P-5 means people lose out on the built-in cooling technology and some extra cushion, but it does free up cash to consider accessories like Sleep IQ Technology or the FlexFit Adjustable Base.

Read our full Sleep Number P-5 review

I-8 if…

  • People Want Full Body Pressure Relief. The 3” comfort foam in the I-8 is designed to relieve pressure in 7 areas of the body and the P-5, and its sister model the P-6, is designed to relieve pressure in only 5 areas. The I-8 adds body contouring to the knees and lower legs and the P-5 does not.
  • Someone Is A Hot Sleeper. The I-8 features Outlast technology, designed to pull moisture away from people at night and redistribute it throughout the night, in the surface of the mattress.

Read our full Sleep Number I-8 review

Personal Opinion

With a $1,400 price difference between a Queen size P-5 mattress and a Queen size I-8 mattress, my preference (and my wallet) would be to favor the P-5 model.

For the price difference, here is what people would get in the I-8 that they don’t get in the P-5:

  • Outlast Technology (to keep you cool at night)
  • 2” additional inches of mattress height – for a total of 13″ of height
  • Duvet style pillowtop
  • 1” foam base pad underneath the air chamber(s)
  • An additional 1” of proprietary PlushFit comfort foam – for a total of 3” of foam
  • 2 additional zones of body contouring in the comfort foam layer – to relieve pressure on your knees and lower legs – for a total of 7 layers.

Overall, you are losing out on cooling technology and a thicker layer of comfort foam with some additional pressure relief points.

There are plenty of mattress toppers, pads, and protectors on the market that helps keep you cool at night. With that in mind, and knowing the popularity of the P-5, I feel inclined to choose that model over the I-8. With the money I save, I could upgrade my bed to add a FlexFit Adjustable Base and get even more out of my Sleep Number bed.

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Katie Golde

Katie manages the day to day operations of the Mattress Clarity news site and reviews sleep products in addition to writing and editing sleep news. She hails from Austin, where she lives with her growing family. She is a Certified Sleep Science Coach and has a master’s degree in Journalism from Northwestern University and has a background in health and science content. Her work can be found in print and online publications like Discover Magazine, USA Today and The Huffington Post.