DENTON (UNT), Texas -- Many hospitals require employees to get yearly flu vaccinations, to protect patients from contracting the flu and to reduce the number of sick days that employees use.

If employees are sleep deprived, however, could their immune responses to a vaccine be negatively affected?

Two University of North Texas health psychologists will determine if sleep patterns act as a stressor on the immune system -- and possibly lead to reduced response to the vaccine, which could result in greater risk of contracting the flu.