Objectives Chronic sleep restriction is highly prevalent in modern society and is, in its clinical form, insufficient sleep syndrome, one of the most prevalent diagnoses in clinical sleep laboratories, with substantial negative impact on health and community burden. It reflects every‐day sleep loss better than acute sleep deprivation, but its effects and particularly the underlying mechanisms remain largely unknown for a variety of critical cognitive domains, as, for example, risky decision making.

Methods We assessed financial risk‐taking behavior after 7 consecutive nights of sleep restriction and after 1 night of acute sleep deprivation compared to a regular sleep condition in a within‐subject design. We further investigated potential underlying mechanisms of sleep‐loss–induced changes in behavior by high‐density electroencephalography recordings during restricted sleep.

Results We show that chronic sleep restriction increases risk‐seeking, whereas this was not observed after acute sleep deprivation. This increase was subjectively not noticed and was related to locally lower values of slow‐wave energy during preceding sleep, an electrophysiological marker of sleep intensity and restoration, in electrodes over the right prefrontal cortex.