FAQ

Limitless is based on The Dark Fields (2001), a novel by Irish writer Alan Glyn. The novel was adapted for the screen by American screenwriter Leslie Dixon.

Some of the effects of NZT, like increased productivity and focus or the feeling of having to keep moving forward is similar to the effects of Adderall and Ritalin. There is also drug called Focalin XR that can help people with focusing and efficiency too. However, the ability to recall all the memories in your subconscious or the ability to process information in the almost superhuman capacity that NZT provides is not an effect of any known drug.

In the USA, the theatrical version was rated PG-13 (for thematic material involving a drug, violence including disturbing images, sexuality and language) by the Motion Picture Association of America (MPAA). For the home cinema release, the US audience is able to buy a DVD or a Blu-ray disc that both include the theatrical version as well as an "Unrated Extended Cut".