Insomnia is a debilitating condition that can cause severe psychological distress and is frequently comorbid with other mental health conditions. Although psychological treatment is effective, it is hindered by cost and availability, while hypnotic sleep medications are recommended for time-limited use and can impair day-time functioning. For these reasons, investigation into alternative treatment options for sleep difficulties is necessary. The present study examined the effect of a multi ingredient micronutrient formula called Daily Self Defense (revised formula of EMPowerplus) on adults suffering from insomnia; following a multiple baseline design. The final sample comprised 14 participants, aged 18 years or older, who were randomised into one of three baseline groups; ranging from one to three weeks in length. Following the baseline phase, participants took part in an open-label trial of Daily Self Defense for eight weeks; after which a three month follow-up was conducted. Although there was a trend towards a small improvement during baseline phase for some measures, there was much greater improvement during the intervention phase. Time series graphs and Modified Brinley plots revealed decreases in insomnia severity, depression, stress and anxiety for 10 out of 12 participants who completed the intervention phase. Cohen’s d, and the percentage of participants showing reliable positive change, confirmed moderate or large effect sizes for all outcome variables. Furthermore, of 12 participants who completed the intervention phase, all were compliant with taking the capsules, and any side effects experienced were mild and transitory. This study provides evidence for the potential of micronutrient interventions in effectively treating insomnia in adults. It also indicates the need for future research utilising placebo-controlled designs as well as comparisons to current available treatments.