Leg cramps and tonic water

I'm 24 weeks and been getting bad leg cramps in the night the last couple of weeks. My midwife suggested drinking a glass of tonic water before bed but from googling this it can help but you are recommended to avoid quinine drinks in pregnancy. I'm thinking it's better not to have it if that's the case but why would the midwife suggest it if it's not safe? Does anyone know any more or have any other suggestions to help the cramps that keep waking me up?!