If taking in the sea air is supposed to be restorative, why can a restful day at the beach end up feeling so tiring? [ Related: 6 of the weirdest things to ever wash up on the beach ]Heat is hard on the bodyIt’s usually the height of summer when we opt to spend our days oceanside, and that means hours in the heat. On the less consequential side, beach fatigue could also, in part, be a byproduct of all this extra, unconscious effort. Couple that dehydration with the fact that many people at the beach opt to drink alcohol over water, and the problem is amplified. Sunburn triggers an inflammatory response, Crandall notes.