Insomnia is a common disorder and cognitive behavioural therapy for insomnia (CBT-I) is recommended as first-line treatment. However, CBT-I is not widely distributed and infrequently available while medication is not indicated for long-term use. To close this evident gap in supply, alternative treatments could be utilised. High-quality research on this topic is scarce, and there is currently no comprehensive publication on the effectiveness of alternative treatments. To address this pressing question, we systematically summarised the existing research on alternative treatments for insomnia. A comprehensive search of systematic reviews and (network) meta-analyses of randomised controlled trials investigating the efficacy of alternative treatments compared to waiting-list control or placebo in adults with insomnia disorder with or without comorbidities was conducted in PubMed, MEDLINE, PsycInfo, and PsycArticles on December 6, 2022, yielding 391 records. Finally, 15 eligible studies were included. Evidence on acupuncture, exogenous melatonin, mind-body interventions and exercise, repetitive transcranial magnetic stimulation (rTMS), valerian, and light exposure was found. Acupuncture, rTMS and mind-body exercises significantly improved sleep quality and insomnia severity but effects on objectively assessed outcomes were inconclusive. Melatonin led to a reduction in both self-reported and objectively assessed sleep onset latency. Light exposure and valerian did not significantly improve sleep outcomes. Overall, the quality of studies was rated as low. Results indicate that alternative treatments are effective mostly on subjective outcomes. However, evidence on the efficacy of some intervention types is sparse and there is a need for high-quality original studies. Future research could investigate whether combining different alternative treatment aspects with CBT-I improves individual treatment.