RESUMO
BACKGROUND: Military special operators, elite athletes, and others requiring uninterrupted optimal performance currently lack options for sleep and mood support without performance-inhibiting effects. Kavalactones, derived from the root of the kava plant (Piper methysticum Forst), have been shown to elevate mood and wellbeing by producing a feeling of relaxation without addiction or cognitive impairment. METHODS: In this placebo-controlled, crossover study (NCT05381025), we investigated the effects of 2 weeks of kavalactones use on cortisol (diurnal salivary), sleep (RSQ-W; Restorative Sleep Questionnaire, Weekly), mood (DASS-21; Depression Anxiety Stress Scale-21), and motivation state to expend (Move) or conserve (Rest) energy (CRAVE; Cravings for Rest and Volitional Energy Expenditure, Right Now) in a cohort of 15 healthy, physically fit young males engaged in a rigorous, two-a-day preparation class for special operations forces qualification. RESULTS: Cortisol, sleep, and mood were within normal, healthy parameters in this cohort at baseline. This remained unchanged with kavalactones use with no significant findings of clinical interest. However, a statistically similar, positive slope for within-group Move scores was seen in both groups during kavalactones loading (first group Move slope 2.25, second group Move slope 3.29, p = 0.299). This trend was seen regardless of order and with no apparent effects on the Rest metric (all p ≥ 0.05). Moreover, a significant between-group difference appeared after 1 week of kavalactones use in the first phase (p = 0.044) and persisted through the end of the first loading period (p = 0.022). Following the 10-day washout, this between-groups divergence remained significant (p = 0.038) but was reversed by 1 week after the crossover (p = 0.072), with Move scores once again statistically similar between groups and compared to baseline at study end. Furthermore, the group taking kavalactones first never experienced a significant decrease in Move motivation state (lowest mean score 21.0, highest 28.6, all p ≥ 0.05), while the group receiving kavalactones in the last 2 weeks of the study had Move scores that were statistically lower than baseline (lowest mean score 8.6, highest 25.9, all p ≤ 0.05) at all time points but the last (p = 0.063) after 2 weeks of kavalactones exposure. CONCLUSIONS: We report a novel finding that kavalactones may support performance by maintaining or rescuing the desire to expend energy in the context of significant physical and mental strain in well-conditioned individuals, even in a context of already normal cortisol, sleep, and mood.
