8" Spring Sensation Hybrid Full Mattress

Update 04/05/21 -- Not Cool By Any Stretch of the Imagination So, because of a recent layoff, I relented and put the old mattress topper on (see below), despite it soaking the smell from the old mattress. I never had problems with heat retention in a mattress before and didn't with this topper. It is a copper infused gel by The Big One and had been used for 2 months prior to getting this mattress and it was not hot. It's still too hot. I'm not sure what to do. Though this mattress has solved shoulder and back problems associated with the old mattress, it just runs way too hot. I'm knocking another star off for that specific reason. With summer coming I may end up sleeping on the floor to stay cool and that's not comfortable either. I'm not inclined to recommend this to anyone unless they have year round air conditioning. ----- This is a new mattress for me, only 3 nights (as of 02/26/21) but I thought I would lend my initial thoughts. Stats: Over 50 years old, petite (under 5'5", under 110 pounds) and a side sleeper. Mattress: Full Size, 12". A bit of a back story: This mattress replaced a used mattress that I got in December because it was the best solution at the time. It was old, lumpy, and had a big dip in it (and not my smell, ew). Due to the dip in it, this created an improper alignment of my spine. Waking up everyday with upper shoulder and neck discomfort closing in on pain, numbness in the right hand and pain in the left hand (thumb). I could only sleep on the left side due to the big dip or I felt I was falling forward. It was not a good situation but it was what it was. A friend noticed my pain and frustration along with how tight and knotted my upper back, neck and shoulders were. I had this Zinus mattress along with a couple of others in my "Wish List" for quite some time and my friend helped me get this mattress because this friend cares about me and my health -- good people to have in your life! I had initially thought of getting the 10" but after reviewing many of the comments, I felt jumping up to the 12" was the better option while keeping the cost of a new mattress relatively lower. So Tuesday my mattress arrived, and it did require assistance to get it up to my second story apartment. These are boxed well, just a bit awkward and luckily I was here when Amazon dropped it off so it was inside the building a few feet -- thank you guys!. It'd be nice if manufacturers of boxes could come up with some kind of handle system on these larger boxes but I digress. After placing it on the bed frame (a Zinus Casey 18-Inch SmartBase Mattress Foundation) It inflated within minutes and I was able to sleep on the mattress that night! YAY! Initially, it felt a bit more firm than I am accustomed to but I could feel my body didn't have any pressure points and while it is firmer, it is also supportive. I was a bit concerned because I thought I liked a soft/plush mattress but this was different than anything I had slept on previously and I was a bit skeptical. The first and second nights took some adjustment since my body had become habituated to tensing up to resist the sloping of my lower back and hips towards the dip in the old mattress which created the massive resistance in the upper back area. But when I woke up this morning, after the third night, I realized my upper back, shoulders, and neck are beginning to relax and my range of motion in that area is better and the discomfort and pain I had is down to about 25% to what I had prior. This is a huge deal. I will say that this mattress runs hotter than I would have hoped. I may need to get a topper like I had on the previous mattress (still have the old one but it smells funky because of the old mattress) to increase some air flow or something. I think that's the biggest ding against this mattress so far. That being said, my initial experience with this mattress is a positive one. Longevity and continued support for my spine will be a test of time. I hope I remember to do updates as time goes on. I am beginning to feel like my old self again after a couple of months with a horrible mattress and am thankful/grateful to my friend for assisting me with this. Proper rest is so important to how we begin our day and I feel more positive than I have in a while.