Sleep is essential for mental and physical wellbeing (Chattu et al. 2018; Medic et al. 2017). Having a properly functioning sleep-wake cycle promotes survival (Worley 2018), adequate energy levels and normal motor and cognitive functioning (Walker et al. 2003; Kesner et al. 2020). Impaired sleep has been linked to a number of health consequences (Medic et al. 2017) such as: negative social functioning, accidents, cardiovascular disease, chronic pain, neurodegenerative disorders, depression, obesity, cancer and all-cause mortality (Chattu et al. 2018; Medic et al. 2017; Irwin et al. 2015; Krueger et al. 2008; Mullington et al 2010). An underlying pathogenesis to these health conditions is inflammation. Poor sleep quality has been shown to increase inflammatory mediators, potentially inducing the adverse physical and cognitive symptoms of sleep loss (Irwin et al. 2015, 2016; Krueger et al. 2008; Mullington et al. 2010). Poor sleep quality may also increase inflammation through increased sympathoadrenal activity, decreased glucose tolerance and neuroendocrine changes (Irwin et al. 2015; Krueger et al. 2008; Mullington et al. 2010)
The endogenous cannabinoid (endocannabinoid) system regulates numerous circadian processes including food intake, peripheral metabolism, and body temperature via the suprachiasmatic nucleus (Vaughn et al. 2010; Ho et al. 2008; Prospero-Garcia et al. 2016; Murillo-Rodriguez et al. 2011) and is involved in the sleep/wake cycle, (Kesner et al. 2020; Murillo-Rodriguez et al. 2011). The endocannabinoid system consists of lipid mediators that act upon specific receptors, including the nervous system (Kesner et al. 2020; Prospero-Garcia et al. 2016; Murillo-Rodriguez et al. 2011) It can also influence temperature regulation, fat storage, mood and behaviour regulation, sensory perception, motor activity, nervous system modulation, and endocrine and gastrointestinal (GI) function (Vaughn et al, 2010) – all previously shown to have an effect on sleep (Vaughn et al, 2010). Endocannabinoid signalling follows a circadian rhythm (Vaughn et al. 2010; Murillo-Rodriguez et al. 2011), such that sleep deprivation could lead to disruption to this cycle (Vaughn et al, 2010). Developing treatment strategies that target the endocannabinoid system could be a potential way to manage sleep disorders and disturbances.
Palmitoylethanolamide (PEA), an endogenous fatty acid amide, works synergistically with the endocannabinoid, anandamide (AEA) (Ho et al. 2008). AEA concentrations are low at sleep onset, increase during sleep and high at wakening (Vaughn et al. 2010; Ho et al. 2008). It is proposed that increased AEA signalling could facilitate deep non-rapid eye movement (NREM) sleep through inducing adenosine release (Prospero-Garcia et al. 2016). However, disturbed sleep is possibly related to impaired AEA signalling (Vaughn et al. 2010). Therefore, an exogenous dose of PEA could possibly restore dysregulated AEA signalling and facilitate better sleep. PEA is also proposed to have an effect on sleep due to its ability to act through transient receptor potential cation channel subfamily V member 1 (TrpV1). Activation of TRPV1 via increased AEA initiates vasorelaxation through a release of vasodilators (Vaughn et al. 2010; Zygmunt et al. 1999) and may facilitate sleep (Vaughn et al. 2010; Ho et al. 2008; Ambrosino et al. 2013; Franco-Cereceda et al. 1989).
Additionally, PEA’s pain-alleviating and anti-inflammatory properties (Canteri et al. 2010; Evangelista et al. 2018; Chirchiglia et al. 2018; Conigliaro et al. 2011; Dalla Volta et al. 2016; Keppel Hesselink et al, 2012; Marini et al. 2012) could reduce pain and inflammation reported to impair sleep (Evangelista et al. 2018). A study by Evangelista et al found that 600 mg of PEA administered to patients awaiting carpal tunnel syndrome surgery significantly improved patient’s overall sleep quality, including an increase in continuous sleep time and a reduction of sleep latency (Evangelista et al. 2018). It was reported that this was due to its mitigation of pain symptoms in the treatment group encountering neuropathic pain, which contributed to their poor sleep quality (Evangelista et al. 2018). Such findings point to PEA as a potential option for sleep disorders.
A limitation to PEA’s therapeutic efficacy is its traditionally poor bioavailability (Gabrielsson et al. 2016). Levagen+® is a clinically studied PEA formulation utilizing cold-water dispersible (CWD) technology (LipiSperse) that significantly increases plasma PEA concentrations by approximately 2-fold (Briskey et al. 2020). Therefore, the aim of this study is to evaluate the efficacy of Levagen+® (PEA) supplementation on sleep quality and quantity in healthy adults with sleep pattern disturbance. It is hypothesised that PEA supplementation one hour prior to sleep onset will improve sleep quality, quantity and onset time.