It's odd isn't it how 'sleep' can differ. I've had a long nine hours and woken feeling absolutely smashing. I can take deep breaths and my lungs feel relaxed somehow. Very occasionally I can have the same nine hours, but on awakening I feel tired still and my breathing doesn't seem to get down to the bottom of my lungs. There must be different qualities of sleep. But sleep I do, Olympic Standard, and I still say it's due to many of the points raised above. Dark room, tons of fresh air, no over-stimulation before bedtime, a bit of healthy exercise during the day, no heavy meal. But one thing will always stop you sleeping - stress. If you have worries or are grieving for example, your mind won't let you shut down. Your eyes fly open and your heart goes bonkers. I've had that at bad times in my life. ( By the way, alcohol is definitely a NO-NO!)