University students have poor sleep hygiene, leading to poorer health. Facets of self-regulation such as planning, behavioural inhibition, cognitive flexibility and working memory were explored in relation to three sleep hygiene behaviours: Avoiding stress or anxiety before bed, avoiding going to bed hungry or thirsty, and making the bedroom restful. One hundred and thirty-seven participants took part in an Internet-based survey over two time points separated by a period of two weeks. Only cognitive flexibility and behavioural inhibition correlated with sleep hygiene. Cognitive flexibility significantly predicted an aspect of sleep hygiene after controlling for past behaviour. However, when past behaviour was controlled for, behavioural inhibition no longer predicted sleep hygiene. Thus, cognitive flexibility may play a role in explaining sleep hygiene; however, behavioural inhibition does not appear as important as previously assumed. Further research could build on this study to determine whether cognitive flexibility can be experimentally improved.