Sleep might also boost aspects of virus-specific adaptive cellular immunity. Compared to wakefulness, sleep in the night following vaccination against hepatitis A doubled the relative proportion of virus-specific T helper cells, which are known to play a prominent role in host-protective immune responses.
Interestingly, in individuals who slept the night after the first vaccination, the increase in the fraction of interferon-γ (IFN-γ)-positive immune cells at weeks 0–8 was significantly more pronounced than in those who had stayed awake on that night.