Islamic State of Iraq and Syria (ISIS) has recently carried out atrocities both in the Middle East and localized terror attacks in several western countries killing hundreds and wounding thousands. Many executions and attacks were broadcast within clever media campaigns containing warnings of future attacks. We examined anxiety of a future ISIS threat along with its association to self-reported sleep difficulties in a sample of adult Israelis (N = 1007). We demonstrated this association in different models beyond the effects of additional potential variables which have been noted to affect sleep, such as reported health, exposure to terror, exposure to ISIS media, psychological variables such as general anxiety, depression and post-traumatic stress disorder symptoms. In all cases, a strong positive relationship between ISIS anxiety and sleep symptoms was obtained. Issues concerning the relationship between anxiety of a future threat and sleep symptoms, as well as the notion of sleep difficulties being a marker for such anxiety, are discussed. (C) 2017 Elsevier Ltd. All rights reserved.