As the post-lunch slump sets in, many office workers opt for a coffee or chocolate to keep their eyes open, risking sleeplessness or a sugar crash. It is at times like this, its inventors believe, that a new wearable device can stimulate users via a tiny pulse that will heighten their mood or bring it down if they want to relax. At first glance, the Doppel resembles a traditional watch, albeit one with the clock face on backwards and worn under the wrist. Behind the stainless steel base is not a timepiece, however, but a vibrating motor that gives off a range of mechanical pulses aimed at improving how the user feels. In a similar way to fast or slow-paced music dictating the natural rhythm of the body, the vibrations from the Doppel can control how alert or relaxed the user is, according to co-creator Jack Hooper. Doppel works with a companion app but once set you can leave your phone behind.