Several modifiable behavioral changes were evident within the sleep–COVID-19–lockdown nexus.

Low sleep quality and high insomnia during lockdown were most associated with late bedtimes and long sleep-onset latency.

Elite, individual-sports, and older athletes were more vulnerable to these lockdown-induced disruptions compared with non-elite, team sports, and younger athletes, respectively.

Female athletes reported lower sleep quality and higher insomnia compared with male athletes irrespective of the lockdown.

Athletes sleep and circadian rhythms were more affected by lockdown compared with those seen in the general population.