All overpriced tat that is surplus to requirement. You don't need thousands of pounds of "smart mattress" to sleep. You need to stop staring at last nights REM/deep/light sleep split on your blue light emitting phone an hour before bed, do something relaxing, maybe take a warm shower an hour before bed, cool your sleeping room and slow your breathing as you lay down. Saved you ... £3000, and presumably some subscription.
For the other two, eat healthier in general, and more green vegetables, respectively.
I guess the mattress goes hand-in-hand with the current sleep tracking trend. Your Garmin, Oura, Whoop or Apple Watch cannot give you good analysis of your sleep based purely off of your heartrate. There is little to no backing for this one metric to prove a sleep score, or readiness score, and by paying attention to these laughably inaccurate scores you just placebo yourself into feeling worse (or better, but usually worse) about last nights sleep.