Residual heat stress improves spatial rotation function, but does not modify attention

Background. We aimed to evaluate the effect on cognitive performance (spatial rotation ability, and workingmemory) after recovery from heat stress when body temperature naturally decreases to initial level.Methods. Whole body hyperthermia was induced with Finnish sauna bathing. Before (PRE) and 90 min after(POST) heat stress (EXP)/ rest (CON) participants assessed their own overall motivation, level of sleepiness andmood. Also Switching task with a combination of the Manikin (Man) and the Mathematical Processing (Math) testwas performed.Results. Level of sleepiness significantly (p < .05) increased 90 min after sauna from 1.88 ± 0.30 (EXP PRE) to3.44 ± 0.45 (EXP POST), but did not change significantly in CON (PRE 2.81 ± 0.53, POST 2.88 ± 0.30). Participantsfelt more fatigue (p < .05) during the POST measurements in both trials (CON 3.88 ± 0.79 and EXP 5.88 ± 1.03)compared with before values (CON 2.75 ± 0.66 and EXP 2.44 ± 0.87); 90 min after sauna fatigue was significantlyhigher (p < .05) in EXP compared with CON. During the EXP POST (1.49 ± 0.12 s) measurements response time inMan task significantly decreased (p < .05) compared with PRE (1.66 ± 0.16 s), and throughput significantly (p < .05)increased 90 min after sauna (EXP POST 42.09 ± 3.28) compared with before values (EXP PRE 38.96 ± 3.31). Noother changes were found in Man ant Math task performance.Conclusion. Residual heat stress increases the level of sleepiness and induces higher feeling of fatigue, but thatdoes not impair attention and concentration. Moreover, residual heat stress improves spatial rotation function.