Gamblers often gamble while experiencing fatigue due to sleep deprivation or cumulative sleep debt. Such fatigue has been shown to make decision makers behave more riskily. The present study aimed to test the role of two cognitive processes, risk perception and risk attraction, in this effect. Two hundred and two participants played twelve hands of a black-jack style card game while either fatigued or reasonably alert. Findings showed that both fatigued and alert participants rated higher risk bets as more risky than lower risk bets, suggesting risk perception was unaffected by fatigue. However, fatigued participants did not rate higher risk bets as less attractive than lower risk bets, and reduced the size of their wager to a lesser extent when objective risk increased. These findings are discussed in relation to the effects of fatigue on motivated tasks and the need for gamblers to be aware of the effects of fatigue.