The study found that people who have attempted suicide have higher levels of the peptide DSIP in their blood, and in healthy people, higher DSIP levels are linked to more impulsive or antisocial traits. It also showed that another peptide, NPY, relates to how well someone handles stress. The research is mostly observational and doesn’t give clear guidance on how to use DSIP for health or performance.

Decreased plasma levels of plasma-neuropeptide Y (NPY) and plasma-corticotropin releasing hormone (CRH), and increased levels of plasma delta-sleep inducing peptide (DSIP) in suicide attempters with mood disorders have previously been observed. This study was performed in order to further understand the clinical relevance of these findings. Examination of correlates between temperament dimensions (Karolinska Scales of Personality (KSP), the Eysenck Personality Questionnaire together with the IVE- impulsiveness scale (EPQI), and the Marke-Nyman Temperament (MNT)) and NPY, CRH and DSIP and serum-cortisol in the dexamethasone suppression test (DST) in 38 suicidal patients and matched controls. NPY correlated significantly and positively with psychasthenia, irritability, and stability and significantly and negatively with validity in patients, but significantly and negatively with muscular tension, psychasthenia, verbal aggression and irritability in controls. DSIP correlated significantly and positively with impulsiveness (EPQI) in controls. CRH correlated negatively with lie in controls. Cortisol correlated significantly and positively with validity, extraversion and verbal aggression and significantly and negatively with inhibition of aggression in controls. NPY may be related to stress tolerance. DSIP seems to be associated with impulsivity/antisocial traits. Non-suicidal patients were not included in the examination. The state of depression or stress seems to influence the correlations studied.