Sheridan Smith has spoken about how a diagnosis of attention deficit hyperactivity disorder (ADHD) has helped her “make sense of a lot of things” in her life. The Olivier award-winner, who will star in the musical Opening Night at the Gielgud Theatre next month, told Vogue “I never know what to say and I overthink”, adding that she found herself constantly “overanalysing” little things, such as the “mums’ WhatsApp group” for her son’s school. She said: “[I’m called] Shadow Sheridan because all I do is lurk.” ADHD includes symptoms such as being restless, having trouble concentrating, and acting on impulse. Symptoms tend to be noticed at an early age, though they can sometimes be diagnosed in adults. Smith, 42, said her diagnosis had helped her understand her “brain’s background noise”. The actor and TV personality’s breakout acting role was as Antony’s girlfriend, Emma, in The Royle Family. She later joined the main cast of the hit comedy Two Pints of Lager and a Packet of Crisps, and starred in stage productions of Legally Blonde, Little Shop of Horrors and Funny Girl. In her 2020 documentary Becoming Mum, she opened up about her mental health issues and concerns that they would resurface after the birth of her son, Billy. Smith will next take on the role of Myrtle in Opening Night, which is based on the 1977 film of the same name. It follows “a theatre company’s preparations to stage a new play on Broadway”, according to the synopsis. “But drama ignites backstage when their leading lady is rocked by tragedy, and her personal turmoil forces everyone to deliver the performances of their lives.” It is estimated that 2.6 million people in the UK have ADHD, and in recent years an increasing number of public figures have opened up about their experience with the condition. They include the reality TV personality Sam Thompson, who spoke about being diagnosed with ADHD at the age of 30 during his appearance on the latest season of I’m a Celebrity … Get Me Out of Here. “It’s weird nobody really spotted it beforehand at school because if you look at all my report cards, every single one is the same. It says: ‘Likable enough guy but lacks focus.’ It’s like staring you in the face,” Thompson said. “If I had known as a kid, not much would have changed, but how you feel about yourself probably changes. I remember crying into my textbooks because I was like, I can’t understand the words that are going into my head.”