My wife get severe crams in leg in sleep.Its severe& painful.
Can any one suggest prventive& correctve measure?

Seek a doctor, this may be restles leg syndrome, or a charlie horse... I don't know, I'm not a physician. But if this bothers her and affects her sleep, I would definitely go to the doctor.

How old is she? Is she on any medication?

I get cramps mostly from lack of potassium.
I take 600 mg calcium, 300 mg magnesium and potassium at night to relax my muscles.

Being the good husband you could see if massaging her legs helps:D

Let's all just back off for a minute. If she is taking any medications, particularly Statins, any advice we give could be dangerous. We first need to know if she is on any meds before prescribing "treatments."

N0help4u agrees: The massage part should be okay though for now though...

Heck yeah!! She would be a very lucky woman to get a massage from hubby.

It's just that Statins (medication used primarily for cholesterol control) tend to cause the problem described in the OP.

I just hate "prescribing" treatment until I get the entire picture.