In a randomized crossover trial with 42 university students, three personalized slow-paced breathing protocols at 40%, 60%, and 80% of each participant's spontaneous breathing frequency were compared. Lower breathing frequencies enhanced subjective relaxation and reduced physiological arousal, shown by decreased heart rate, increased heart rate variability, and increased peripheral skin temperature. Lower frequencies also shifted prefrontal neurophysiological arousal, decreasing relative delta power and increasing relative alpha and beta power. Prior experience with relaxation techniques strengthened subjective benefits, while higher anxious-depressive symptoms were linked to greater perceived stress after slow-paced breathing. Personalizing and optimizing breathing parameters may enhance relaxation and self-regulatory capacity.
During sleep, the human brain continues to process unexpected sounds, but the neural code becomes delayed, more redundant, and less rich as consciousness wanes. Twenty-nine participants heard an oddball sequence of tones while awake and during an 8-hour sleep opportunity. Prediction error responses occurred in all sleep stages (N1, N2, N3, REM). Mutual information analysis showed a substantial reduction in encoded prediction error information, especially during N3 and REM, even though electrical brain responses (ERPs) grew larger in deeper NREM sleep. Co-information analysis revealed that neural dynamics became increasingly redundant with deeper sleep. The neural code differed between wakefulness and sleep but was largely shared between N2 and N3 stages.