Most vacations seem to have strong, but rather short-lived effects on health and well-being (H&W). However, the recovery-potential of relatively long vacations and the underlying processes have been disregarded. Therefore, our study focused on vacations longer than 14 days and on the psychological processes associated with such a long respite from work. In the present study, we investigated (1) how health and well-being (H&W) develop during and after a long summer vacation, (2) whether changes in H&W during and after vacation relate to vacation activities and experiences and (3) whether changes in H&W during and after vacation relate to sleep. Fifty-four employees reported their H&W before, three or four times during and five times after vacation. Vacations lasted 23 days on average. Information on vacation experiences, work-related activities and sleep was collected during vacation. Vacation activities were assessed immediately after vacation. H&W increased quickly during vacation, peaked on the eighth vacation day and had rapidly returned to baseline level within the first week of work resumption. Vacation duration and most vacation activities were only weakly associated with H&W changes during and after vacation. Engagement in passive activities, savoring, pleasure derived from activities, relaxation, control and sleep showed strong relations with improved H&W during and to a lesser degree after vacation. In conclusion, H&W improved during long summer vacations, but this positive effect was short-lived. Vacation experiences, especially pleasure, relaxation, savoring and control, seem to be especially important for the strength and persistence of vacation (after-) effects.