I first saw the Zeez featured on the Gadget show and having struggled with sleep for many years I decided to give it a go. The option of being able to rent one appealed to me as it meant I would have a chance to try it for an extended period without committing to the full purchase, especially as my sleep can be very unpredictable! As with many people who suffer from poor sleep, I've tried many things over the years including a CBT course, which didn't help at all! After trying the Zeez pebble for a few nights I noticed a definite improvement in sleep quality however after a couple of weeks or so I seemed to go back to square one with some nights of very poor sleep returning. This was quite devastating after such a positive start! I got to the point where I thought the Zeez had actually failed in some way, so I emailed Anna (who is incredibly knowledgeable and helpful), who after a brief chat advised me where I was going wrong. Essentially I had not been taking enough Magnesium. The tap water is pretty awful where i live (East Anglia) and I’d not been helping by double-filtering it (I was using a filter jug and then filling a filtered bottle) as this improved the taste, but had the effect of filtering out the vital minerals, including magnesium. Anna also informed me that it’s also possible to drink too much water (magnesium is water-soluble and so can be diluted by drinking too much water). As soon as i realized this I can definitely say my sleep had worsened in line with switching to using filtered water rather than bottled mineral water. Anna suggested a better magnesium supplement (not all magnesium is the same, see the Zeez site for further info) and I've found Magnesium Citrate Powder to be the most effective as it's more easily absorbed than tablet form, it's also easily added to a glass of water or juice. I’d always thought there was some sort of link between the water I was drinking and sleep patterns, I just didn’t know what! As it says on the Zeez site Magnesium is essential for good sleep, now I know this for sure I don't have any issues in taking a Magnesium supplement. I've also struggled with histamine intolerance in the past (I had an overactive immune response following a brush with Lyme Disease and a very high dose of antibiotics), increasing the amount of histamine in my system. which also has an effect on sleep. I saw a Nutritional Therapist (https://www.youmeandvitality.com/) who was excellent and helped me to diagnose this. I would highly recommend going down this route if you suspect there may be other factors affecting your ability to sleep. It is surprising how much diet can affect your general well-being and sleep, unfortunately, there is nowhere near enough education on this subject and I firmly believe diet and nutrition should be at the forefront of medical diagnosis. Overall the Zeez has definitely improved my sleep and I feel that the sleep quality I'm getting is much better and almost feels like the sleep I used to get many years ago before insomnia took over! I have now purchased the Zeez after the rental period has ended, I had no doubt whatsoever in going ahead with the purchase. If you are struggling with sleep I would highly recommend trying a Zeez.