This study examined a two-dimensional approach to assessing affective states among good and poor sleepers using the self-assessment manikin (SAM), a brief non-verbal self-report measure of affective states with separate ratings of valence and arousal. A sample of 286 undergraduate students completed the Pittsburgh Sleep Quality Index (PSQI) and the SAM. Participants were classified post hoc as either good (PSQI ≤ 5) or poor sleepers (PSQI > 5) using the PSQI and used the SAM to rate their current affective states (day) and their affective state at bedtime (night) the previous night. Compared to good sleepers, poor sleepers reported more negative affect and arousal at night and more negative affect during the day. Among poor sleepers, lower sleep quality and shorter sleep duration on the components of the PSQI were associated with more negative daytime valence. Among good sleepers, higher scores on the sleep medication and daytime dysfunction components of the PSQI were associated with more negative daytime valence. These findings indicate that the SAM appears to detect differences between good and poor sleepers on both valence and arousal of current daytime and retrospective night-time emotional states. This approach could be useful for the assessment of affective states related to sleep disturbance.