Hello.
Just inability to sleep or does she have another problem.
If nothing else then she should evaluate any recent changes in her life. Like work life , friend circle, new project or any thing new in her children's life. All these life changes cause transient
insomnia. This will initially need
sleep hygiene. Means.....no to bed the whole day, how so ever tired she is......no to coffee or tea after 6 in eve......no stimulating tv watching or strong music before sleeping......light books and light music before sleeping...get up at a fixed time in morning what ever was the situation in the night...
Even after following all these if she is not able to sleep , than she will need intervention of a
psychiatrist. And please follow the advice and follow up as asked ....don't try to manage it yourself...it cause more harm than benefit
Take care