Insomnia is living up to its name, as the Channel 5 thriller has left viewers having nightmares after watching episode 1.

The Vicky McClure six-parter landed on Sunday night (July 06, 2025), and made quite the impression on those watching. It follows successful lawyer Emma Averill as her life slowly falls apart night by night – when she cannot sleep.

Yep, we’ve all been there!

Like The Castaways, and The Ex-Wife, the series first streamed on Paramount+ before arriving on C5. The original drama is based on the bestselling page-turner of the same name by Sarah Pinborough.

The book is described as a gripping crime thriller from the bestselling author of Behind Her Eyes. That was also turned into a TV series for Netflix, and had a twist literally no one saw coming. And Insomnia is following suit…

Fans react to Vicky McClure thriller Insomnia on Channel 5

Channel 5 viewers seemed to enjoy tense thriller Insomnia after episode 1. If being scared witless is the same as enjoyment! While billed as a thriller, the series could easily be described as a horror in some places – with its fair share of jump scares.

One fan wrote: “I’m really enjoying #Insomnia – creepy and compelling.”

Another said: “This has given us the heebie-jeebies #Insomnia.”

A third added: “We’re going to have nightmares now #Insomnia.”

“I am really enjoying #Insomnia,” said another, “although I’m upset I couldn’t binge-watch it. It takes very relatable character (busy working mother with insomnia) and then pushes her further and further till she’s questioning her own sanity.”

One more said: “This [bleeped] with my mind. It was lovely but disturbing at the same time. #insomnia #twisty.”

“Really enjoyed Insomnia. Looove Vicky McClure in pretty much everything she is in!” said another.

Yet another fan enthused: “If you haven’t watched Insomnia, do so. Adapted from the book of the same name. It is excellent viewing.”

“It’s an eye opener,” added another viewer.

Insomnia on Channel 5 episode 1 recap

Insomnia introduced high-flying family lawyer Emma Averill, who was enjoying her hard-won dream life in a lovely big house with a rather sexy husband… But it quickly started turning into a nightmare when she found she could not sleep. With a seemingly traumatic past behind her, she feared she might be “going mad” just like her mother did… Could Emma have her mum’s “bad blood”? And what exactly happened to her mum that she was so afraid of history repeating itself?

In episode 1, Emma began suffering from insomnia – and hallucinations – as her 40th birthday approached. This would be annoying for anybody obviously but, for Emma, there were more sinister connotations. Her own mum Patricia also started suffering from insomnia before suffering a psychotic breakdown on her 40th birthday.

What happened to Emma’s mum?

At the same time, Emma’s estranged (and secretly pregnant) sister Phoebe returned after a long absence. She told Emma that their mother was very ill after brutally smashing her head against a mirror. It was clear Emma had NO love for the woman who gave birth to her. But why? Well, some seriously scary flashbacks hinted at the mum’s state of mind when the sisters were younger – horrifyingly she had attempted to smother Phoebe to death with a pillow.

Bizarrely, Emma kept all this from her husband of 20 years. We discovered that Robert believed Emma’s mum was already dead, that she’d died on her 40th birthday. And that wasn’t all Emma was keeping from him. Her sister Phoebe subsequently confronted her, saying: “Your husband doesn’t know what happened to us when we were kids. That isn’t healthy.”

As episode 1 of Insomnia neared its conclusion, it appeared more and more apparent that Emma was beginning to act strangely like her mother did before her breakdown – including repeating numbers out loud. Later, Emma visited her mum in the hospital to confront her. But, in a chilling scene, her previously unconscious mother clutched her arm and gasped aloud. Shudder.

Read more: Five best bingeworthy thrillers on Channel 5.com

Insomnia episode 2 airs on Monday, July 07, 2025 at 9pm.