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