Sleep is hypothesized to have a role in the regulation of the immune system. This study evaluated the nocturnal expression of cellular adhesion molecules, Mac-1 and L-selectin on monocytes and lymphocytes during a full nights sleep and following a partial night of sleep deprivation (PSD). Healthy male subjects (n=16) had an increase in the percentage of Mac-1 positive lymphocytes across the baseline night. Whereas, the percentage of Mac-1 positive lymphocytes was reduced and L-selectin positive lymphocytes and monocytes were greater during the PSD night as compared to the baseline night. These data indicate that acute sleep disruption is associated with alterations in cellular adhesion molecule expression, with implications for the regulation of immune cell trafficking.