I used to have back trouble at night (a muscle near my hip sometimes spasms, which woke me up) but it is mostly gone now I roll out my legs with a foam roller before bedtime. I roll the quads, IT bands, and inner thighs, and that seems to stop tight leg muscles tugging my hips which in turn stops my sacroiliac joint getting upset. If I need something more targeted than a foam roller then I lie on a lacrosse ball (dense rubber) to get into tight muscles around the hip. Obviously different things work for different people, but I'm a huge proponent of foam rollers and a lacrosse or tennis ball for treating pain linked to tight tissue.

On the mentioned page you can find a lot of yoga positions to stretch the psoas. But for the Quadratus Lumborum stretch only one position is mentioned and the corresponding yoga pose is probably not as effective as the mentioned in which one leg rotates behind him, off the bed. Any other Quadratus Lumborum streches?

I just found this link and it seems to be very helpful for people who experience lower back pain in the morning: http://www.subdude-site.com/WebPages_Local/RefInfo/StretchExerciseEtc/BackPainSolutions/LowBack_MorningPain/lowBack_morningPain.htm This way you know which yoga poses you should hold longer and do on a regular basis. Hope it also helps other readers.

I just feel my lower back since recently again. Obviously the viscoelastic foam on my matress has lost its supportive property after 4 years already. Because when I bought it it got better right away.

On another webpage it was mentioned that those pointelastic matresses like viscoelastic foam or latex just prevent you from moving around and make your back even worse in the long run. They mentioned Feldenkrais theory. Both my cats got Asthma and I just read that there is something in those foam matresses which triggers Asthma. Therefore I don´t want viscoelastic foam again. Thus I might buy one of those super expensive 100% natural organic latex matresses. Or are there other suggestions?