Thymoquinone-rich black cumin oil improves sleep quality, alleviates anxiety/stress on healthy subjects with sleep disturbances– A pilot polysomnography study

Introduction: Insomnia, the inability to get sleep or sleep well at night, is a universal health problem. In the present single-arm, open-label, pilot study, the safety and efficacy of a thymoquinone-rich (5% w/w) black cumin oil (Nigella sativa) (BCO) was investigated for the first time, among healthy subjects characterized with significant sleep problems.Methods: Fifteen subjects were selected for the study and were provided with softgel capsules of BCO (200 mg x 1/day, after dinner) for 28 days. Polysomnographic analysis was performed to assess sleep quality, sleep efficiency and sleep latency (primary outcomes) at the beginning (visit 2) and after 7 days of supplementation (visit 3). Sleep quality index, anxiety and stress (secondary outcomes) were also measured at the beginning and at the end of the study period (28 days) using the validated questionnaires Pittsburgh Sleep Quality Index (PSQI), Depression Anxiety Stress Scale-21 (DASS-21) and Hamilton Anxiety Rating Scale-A (HAM-A), along with the measurements of cortisol and safety parameters.Results: The results suggested a significant improvement in primary outcomes such as total sleep time, sleep latency and sleep efficiency with an increase of 82.49 % in Non-Rapid Eye Movement (NREM 3) and 29.38 % increase in Rapid Eye Movement sleep (REM sleep). The secondary outcome measurements also showed a significant reduction (P < 0.05) in anxiety and stress as evident from DASS-21 and HAM-A scales, with significant reduction in Cortisol. Haematological and biochemical analysis demonstrated the safety of BCO during the study period.Conclusion: Supplementation of BCO was safe and found to significantly improve the sleep quality and ameliorate stress and anxiety. [Clinical Trial Reg No: CTRI/2018/03/012,391 dated 07/03/2018]