Delta sleep-inducing peptide (DSIP) is a naturally occurring neuropeptide, which was originally isolated from rabbit brain in 1977 . DSIP peptide is a nonapeptide that is normally produced in the hypothalamus of the brain and targets multiple biological sites, including some within the brainstem . DSIP induces sleep and this has been confirmed in many animals and in human studies [3, 4]. Most importantly, DSIP promotes a specific type of deep sleep known as slow wave deep sleep, which is characterised by a certain pattern of brain waves. Slow-wave sleep is particularly important for health since it is the constructive phase of sleep where the body repairs itself. During slow-wave sleep growth hormones are secreted to facilitate muscle repair and growth and tissue repair . During this time, the brain is also able to detoxify and reorganise and glial cells within the brain are recharged with glucose . A neuroprotective effect attributed to DSIP has also been demonstrated in rats along with a reduction in mortality. DSIP is normally present in small amounts in the blood and the brain and the concentration of DSIP fluctuates over a 24-hour period . In healthy individuals, the concentration of DSIP is low in the mornings and increases in the afternoon. When compared with many other peptides, DSIP is unusual because it can freely cross the blood�brain barrier and it is readily absorbed from the gut without being denatured by enzymes [7, 8]. DSIPs have been found in high concentrations in human milk and may be related to the ability of a milk feed to induce sleep in infants . Several clinical uses for DSIP already exist and the neuropeptide has been successfully used for the treatment of alcohol and opioid withdrawal. DSIP showed immediate onset of action and a favourable and lasting suspension of withdrawal symptoms. Patient anxiety also resolved within hours and no major side effects were reported . DSIP 5mg should be reconstituted with BAC water and administered slowly via subcutaneous injection in the afternoon. The peptide has a duration inside the body of around 20 hours in humans . The biological effects of DSIP are dose dependent and up to 5 mcg of the peptide can be used daily. As DSIP is a naturally occurring peptide, reported side effects are rare. However, normal physiological concentrations are usually low and higher doses may induce some minor side effects. In some human studies, transient headache, nausea and vertigo have been documented to occur in some patients. References 1. Schoenenberger, G.A. and M. Monnier, Characterization of a delta-electroencephalogram (-sleep)-inducing peptide. Proceedings of the National Academy of Sciences of the United States of America, 1977. 74(3): p. 1282-1286. 2. Graf, M.V. and A.J. Kastin, Delta-sleep-inducing peptide (DSIP): An update. Peptides, 1986. 7(6): p. 1165-1187. 3. Aliautdin, R.N., V.N. Kalikhevich, and V.I. Churkina, [Hypnogenic properties of the delta-sleep peptide and its structural analogs]. Farmakol Toksikol, 1984. 47(3): p. 26-30. 4. Susic, V., The effect of subcutaneous administration of delta sleep-inducing peptide (DSIP) on some parameters of sleep in the cat. Physiol Behav, 1987. 40(5): p. 569-72. 5. Sassin, J.F., et al., Human growth hormone release: relation to slow-wave sleep and sleep-walking cycles. Science, 1969. 165(3892): p. 513-5. 6. Eugene, A.R. and J. Masiak, The Neuroprotective Aspects of Sleep. MEDtube science, 2015. 3(1): p. 35-40. 7. Banks, W.A., A.J. Kastin, and J.K. Selznick, Modulation of immunoactive levels of DSIP and blood-brain permeability by lighting and diurnal rhythm. J Neurosci Res, 1985. 14(3): p. 347-55. 8. Banks, W.A., et al., Entry of DSIP peptides into dog CSF: Role of physicochemical and pharmacokinetic parameters. Brain Research Bulletin, 1986. 17(2): p. 155-158. 9. Graf, M.V., C.A. Hunter, and A.J. Kastin, Presence of delta-sleep-inducing peptide-like material in human milk. J Clin Endocrinol Metab, 1984. 59(1): p. 127-32. 10. Dick, P., M.E. Grandjean, and R. Tissot, Successful treatment of withdrawal symptoms with delta sleep-inducing peptide, a neuropeptide with potential agonistic activity on opiate receptors. Neuropsychobiology, 1983. 10(4): p. 205-8. 11. Schneider-Helmert, D. and G.A. Schoenenberger, Effects of DSIP in man. Multifunctional psychophysiological properties besides induction of natural sleep. Neuropsychobiology, 1983. 9(4): p. 197-206.