Many people hear that kratom can be taken to battle sleeping problems or to be able to relax better. Sometimes insomnia can be caused (partly) by stress and anxiety. So being able to relax and feel relaxed could already help some people to be better able to sleep.

What strains would be best for sleep and anxiety

Usually the red strains (Red Borneo, Red Malay, Red Sumatra etc) are the most relaxing and most sedating, therefore the red strains should be the first choice for people who look for kratom to fight sleeping disorders and anxiety. However, everybody reacts differently to different strains so it may be beneficial to try out various (red but perhaps also green) strains to find out which strain(s) work best for yourself.

How much to take for sleep and sedation/relaxation

This is also a matter of experimenting. Everybody reacts differently to a given dosage. it depends on your body chemistry, your mind, your metabolism, your weight, your age, your general physical condition and so on and so on, so one should never listen to somebody else to find our how much to take.
It is said that the higher the dosage the more relaxing and sedating the kratom becomes but even that is not always true and that also depends on how long you have been using kratom for example. The higher the tolerance one has the more one should take (but we think one should never take more then 10 grams).

Its also notable that people who just start out using kratom may in the beginning experience the UPLIFTING and ENERGIZING effects more then the sedating and relaxing effects. This can mean that if you just start using kratom EVEN THE RED STRAINS, you may have more trouble falling asleep with the kratom then without the kratom. It needs time for the body to adapt to kratom and it seems that the uplifting effects are initially more prominently felt then relaxing effects.