**5. Future Directions**

There are numerous nutrients and foods that have demonstrated efficacy in isolation for enhancing sleep quality and quantity. As humans rarely consume single nutrients in isolation, and typically enjoy a variety of nutrients as part of mixed meals, it is important to clarify how the co-ingestion of food and supplements can help or hinder sleep. This information would not only be beneficial for athletes within the daily training environment, but also when traveling and crossing multiple time zones with national and international travel.

The growing interest in monitoring athlete sleep has led to an increase in commercial sleep technology (wearables such as Fitbit ™ and Whoop ™, nearables such as ResMed S+ ™, and smartphone applications). These consumer-based technologies have advantages in terms of low-cost and ease of use, however the reliability and validity of many of these devices remains to be established. Although caution needs to be taken when implementing these commercial sleep technology devices at present, the market for sleep monitoring technology is expanding rapidly. Ideally, this expansion will occur alongside research on the reliability and validity of these devices for use in applied settings.

With a plethora of supplements now available in different forms (powder, liquid, capsule), investigation is also required on the most effective form(s) of supplement to consume. For example, tart cherry is available as a liquid, powder, and in a capsule. Understanding the most effective dosage (for example g per kg body mass), timing (acute or chronic consumption), and the most effective supplement form (liquid, gel, powder, capsule), would enable practitioners to more accurately individualize and prescribe nutritional interventions and supplements to aid sleep. More work is needed to establish optimal nutrient dosing relative to body mass, rather than absolute dosing (fixed amount(s) of nutrients) used in the majority of existing studies.
