Circadian rhythms, time zone jumping impacts NBA performance: study

Home-town advantage may take on a new relevance for pro sports teams with research showing that crossing time zones could impact match performance.

Nationwide sports leagues play games across multiple time zones. The US has 5 such time zones across which its major professional basketball, football and baseball teams travel, forcing them to deal with jet lag and altered sleep patterns.

Now an analysis by Turkey’s Dokuz Eylül University suggests the direction of travel may confer an advantage for those living in the west of a country, at least when it comes to the US teams playing in the top-level NBA.

Disruptions to the human circadian rhythm and sleep-wake cycle were considered as a factor a team manager could tap into, in order to maximise playing preparation and advantage.

To come to that conclusion, they analysed more than 25,000 pro basketball games across 21 seasons. For those teams with home games played in the Pacific Daylight Time zone – currently the Portland Trailblazers, Sacramento Kings, Golden State Warriors, LA Lakers and LA Clippers – the winning percentage against those from the Eastern time zone (EDT) is 63.5%.

In reverse, where EDT teams host PDT rosters, win percentage was at 55.0%.

Teams that play ‘away’ in a time zone ahead of their ‘home’ time, were also found to be more likely to win their next match on friendly territory. This, the study team suggests, is due to a delayed re-synchronisation of their circadian rhythm to their local time zone.

“One of the most important results of this research for the home games of the NBA teams is that while travelling to the west increases the performance, travelling to the east decreases the performance,” says Dr Firat Özdalyan, a sports physiologist from Dokuz Eylül University, who led the research published today in the journal Chronobiology International.

“Another notable finding is that the success of NBA teams increases when they are fully adapted to the local time for away games.”

Fatigue a variable factor

But it’s not necessarily all down to the circadian rhythm. The research team couldn’t factor in overall team performance – more teams play in the US’ east, rather than west, meaning overall roster ability could influence the results.

The researchers also note that fatigue from long-distance travel – as opposed to impacts on the sleep-wake cycle – were more likely to blame for poor performance.

Regardless, smart teams could develop strategies to minimise the impact of disrupted sleep rhythms in their interstate travel plans.

“Home teams who will be exposed to such a circadian rhythm phase shift travelling from west to east should be mindful of these potential performance detriments when constructing game plans,” says Özdalyan. “It can be suggested that coaches of away teams should bear [the low shooting success] in mind during the game preparation period.”