Exercise Factors: • Timing of exercise – should be done >3h before bed • Duration of exercise – should be >30 minutes • Intensity of exercise – should be >65% HRmax
2. High-Intensity Interval Training (HIIT) Exercise intensity is one of the acute factors influencing sleep effects after exercise, as is aerobic fitness changes. HIIT includes high-intensity bouts interspersed with active rest bouts of a lower intensity. HIIT includes not only sprint-like activities (i.e. spin class, track workouts) but also metabolic conditioning classes like Tabata workouts. This type of exercise induces significant fatigue (both mental and physical) and is extremely effective at improving aerobic fitness. Because of this, it is thought to be an effective exercise method for improving sleep quality and quantity. No studies have investigated the effects of HIIT in healthy participants. However, given the effects of HIIT on aerobic fitness, one may expect them to be similar, if not slightly greater, than those observed in traditional aerobic training regimes. In participants with co-morbidities involving sleep disturbances, such as rheumatoid arthritis and sleep apnea, the results of HIIT programs appear promising Rheumatoid arthritis and other inflammatory illnesses are commonly associated with sleep disturbances. And these are thought to exacerbate pain and symptoms of dysfunction.
Inflamation and HIIT There is a bi-directional relationship between inflammation and sleep in which inflammation disrupts sleep, while good sleep quality reduces inflammation. HIIT can independently improve sleep and inflammation, effectively improving disease-related outcomes (Loppenthin et al. 2014). HIIT in sleep apnea patients also shows promising results. After a 12-week HIIT program in obese sleep apnea patients, aerobic fitness was improved, apnea related events were reduced, and daytime sleepiness was reduced compared with controls (Karlson et al. 2013).
Timing and HIIT Takeaways As with aerobic exercise, the time of day the HIIT is performed determines its effect on sleep that night. In healthy soccer players, it was found that HIIT training done in the evening disrupted sleep while HIIT in the morning did not (Vitale et al. 2017). 21