We see Emma start to have blackouts from her sleep deprivation and wake up in random locations such as outside in the woods, as well as by an almost over-flowing bath tub, with no recollection of how she got there.

“I’m the one she said would end up like her, who had the bad blood,” Emma says, revealing her anxiety about whether she has inherited her mother’s sleep struggles. Before, Emma’s sister, Phoebe (played by her Line of Duty co-star Leanne Best) tries to stage an intervention: “You’re not sleeping Em, you don’t know what you’re doing half the time!”

She also hints at some trauma in Emma’s past that could have triggered this breakdown and insomnia, as she says: “Your husband doesn’t know what happened to us when we were kids. That isn’t healthy.’

But the creepiest part of the trailer is that it opens and and closes with one terrifying statement, which Emma initially makes to her son: “There is only one monster in this house, and do you know who it is? It’s me.”

Insomnia: Vicky McClure's new thriller releases a tense trailer