Ensuring proper rest for its marquee players has been one of the most pervasive issues affecting the NBA the last several seasons, prompting a lengthening of the schedule and a reduction in games on back-to-back nights and the elimination of stretches with four games in five nights. While that league-wide initiative will aid every team’s recovery this season, the Chicago Bulls are among the organizations adding layers of player monitoring, including a renewal of its partnership with sleep-coaching platform Rise Science.

Enough convincing data was collected in the first season of their collaboration that the Bulls decided to move morning shootarounds back an hour, from 10 a.m. to 11, because players were shown to get, on average, 26 to 28 more minutes of sleep with the later start time.

“Hopefully that reflects in a more recovered team,” Bulls director of sports performance Chip Schaefer told SportTechie.

Rise features a sensor-laden ribbon placed under a player’s mattress where, through the advanced scientific discipline of ballistocardiography, heart-rate variability is monitored. That data provides calculations of sleep and recovery levels. All such tracking devices are voluntary, per the NBA’s collective bargaining agreement, and Schaefer said “a handful of players” opted in and gave “very positive feedback.”

Having objective sleep information helped changed some behaviors, he said, and reinforced the league’s long entrenched napping ritual. “It all counts,” Schaefer said. Rise, which also offers personal input with a sleep coach, helps empower players to craft their own sleep programs.

“The main thing that we found is that these guys need help structuring this,” Rise co-founder and CEO Jeff Kahn said in an interview this summer.

The Bulls are using this sleep data in conjunction with other methods of workload monitoring and rest tracking. Before Schaefer, who has a Ph.D. in health science, returned for its second tour with the Bulls before the 2016-2017 season — he was a part of six championship seasons from his first stint during Michael Jordan’s tenure, before working with five Kobe Bryant-led Los Angeles Lakers title teams, meaning he has more rings, 11, than fingers — Chicago had been offering players STATSports’ Viper wearable for practice usage. But rest was so essential that many teams, like the Bulls, had too few vigorous practices to justify the expense, so the team began utilizing Firstbeat, a Finnish company that monitors heart-rate and a few other biometrics. No wearables are currently permitted during games, so workload has to be extrapolated from the external motion analysis of Second Spectrum’s optical cameras.

Additionally, Schaefer’s staff also collects daily RPEs, a player-given Rating of Perceived Exertion on a 1 to 10 scale. Though this information is inherently simple and subjective, Schaefer said the medical literature validates its use, which is why he’s been collecting those data points for nearly three decades, dating back to Phil Jackson’s time as Bulls coach. Particularly during two-a-day sessions during training camp, Jackson would ask Schaefer for a report between practices to know how much exertion the players reported in the morning.

Schaefer said a similar rapport has developed with current Bulls coach Fred Hoiberg, who’ll ask before training, “How hard should I push them today?”

“A lot of the subjective data we collect, we feel is important, too, but to reality truly analyze stuff, you want to have some objective numbers to work with,” Schaefer said of the advantage of pairing Rise and Firstbeat with the RPEs.

While an outlier day or two of poor rest is something that’s expected from time to time, Schaefer said his staff will have personal interviews with players who might string together several sluggish days consecutively. “If I were looking at low rest and recovery numbers, which we do, those things get our attention,” he said. (Incidentally, Schaefer said Jordan and Bryant were rare “high-energy” players who could perform optimally without long sleeps; during Chicago winters, the Bulls might arrive at Orlando’s Grand Cypress resort at 2 a.m. after a late flight, yet Jordan would be out for the first tee time at 6 a.m.)

“It’s a huge problem in the travel sports, what I call baseball, basketball and hockey,” Kahn said. “Sleep and fatigue is a huge problem for them.”

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There are other sleep-monitoring methods, such as wrist wearables that track motion, but the Bulls believe Rise’s program is better even if traveling with the ribbon sensors is impractical (and the players weren’t keen on trying them on the road last year). Given people’s phone habits these days, with the propensity of looking at a device just before sleep and as soon as one wakes up, Rise could provide some rough sleep data based on phone usage, too.

“We felt there was enough data to collect at home,” Schaefer said. “What we are looking at is particularly back to backs and late-night returns, what their sleep patterns were — not to be intrusive on them but rather to advise us and our coaching staff on the scheduling of practices and shootarounds and things like that.”

The next step, after more data is collected, might be a research project in running correlational analyses of rest numbers with performance metrics.

“I think it’d be very helpful not only to the NBA but to the world of professional, elite sports in general,” Schaefer said.