#95 - Circadian Rhythms, Travel, and Athlete Optimization with Dr. Cheri Mah

Dr. Mah emphasized that jet lag isn't just from flying; social jet lag (shifting sleep on weekends) causes similar desynchrony. She advises having a framework rather than reacting upon arrival. The rule of thumb: 1 day per time zone to acclimate. Pre-flight: sleep banking and gradual shifting reduce the effective time zone change. In-flight: changing watch to destination time helps mental alignment. Post-flight: sunlight is a powerful zeitgeber; timing matters based on travel direction. Matthew Walker added his personal tactics: immediately set all clocks to destination time, use melatonin (3 mg, 45 min before bed), and take a hot bath/shower 90 minutes before bed to aid core temperature drop. He also brings his own snacks to avoid poor airplane food that can disrupt sleep and gut.

Dr. Mah's study in baseball players demonstrated that 5 days of sleep extension (1 extra hour) led to 66 ms faster visual search reaction time and 122 ms faster cognitive processing speed. She likened it to carb loading. Matthew Walker noted the distinction from trying to repay sleep debt after deprivation, which is less effective for some functions. This approach is more manageable than multi-week sleep extension protocols. The mechanism may involve reduced sleep pressure and improved synaptic homeostasis, though not explicitly discussed.

Dr. Mah and Matthew Walker discussed the nappuccino as a favorite tool. Research shows it outperforms caffeine alone or nap alone. The nap reduces sleep pressure, while caffeine blocks adenosine receptors, providing a synergistic effect. It's ideal for combating post-lunch dip or pre-performance sluggishness.

Dr. Mah recommends this as a simple, low-effort strategy to combat inconsistent bedtimes. She also suggests writing down a sleep plan and identifying obstacles. The alarm is part of a broader approach to intentionality. She finds that athletes who vocalize their plan and anticipate challenges are more successful.

Dr. Mah finds this exercise highly effective with her athletes. It transforms vague intentions into concrete plans. She also emphasizes making sleep a team effort, involving spouses or teammates for accountability and support. The system around the individual (e.g., team schedule, family) must be aligned with the sleep goal.

Dr. Mah stressed that the system around an individual is often more important than individual willpower. For athletes, if the organization demands early morning treatment, it undermines sleep. She advises leveraging travel time (without kids) for sleep extension. For parents, she acknowledges the challenge and recommends power naps and nappuccinos.

Dr. Mah was inspired by the original study by Dr. Roger Smith (her mentor) and extended it to 40 seasons. The advantage stems from the body clock: West Coast teams play night games (7–10 p.m. local) closer to their biological peak performance window of 4–8 p.m., while East Coast teams are playing at a later body clock time (10 p.m.–1 a.m. Eastern body time). This misalignment impairs physical and cognitive performance. The finding held regardless of which coast the game was played on, emphasizing the internal clock's role. Dr. Mah noted this is an underappreciated factor in team performance and hopes it encourages organizations to consider circadian science in scheduling and travel.

Dr. Mah conducted the study in professional baseball players, using a visual search reaction time task analogous to pitch recognition. The sleep loading group extended sleep by 1 hour (e.g., from 5 to 6 hours, or 6 to 7 hours) for 5 days. The control group maintained habitual sleep. Results: 66 ms faster reaction time and 122 ms faster cognitive processing speed. Dr. Mah emphasized that 180 ms is the time to react to a fastball, so these millisecond gains are meaningful. The concept is to build a 'sleep credit' before anticipated sleep debt, reducing the performance decrement. This differs from trying to repay sleep debt after deprivation, which is less effective for some brain functions. The host, Matthew Walker, praised the elegance of building credit before debt rather than repaying after.

The project ran from 2016 to 2018, with predictions published before each season. Red alert games (highest risk) were correct 76–86% of the time. Dr. Mah found that fatigued teams often couldn't recover if behind at halftime or third quarter; e.g., in one season, teams were 1–32 when behind or tied at halftime. The NBA subsequently reduced four-in-five-nights, back-to-backs by ~30%, increased days off after multi-time-zone travel, and cut travel by 8% over a decade. Commissioner Adam Silver acknowledged the resting issue as a major concern. Dr. Mah credits the league for responding to science, though she remains humble about her role.

Dr. Mah and Matthew Walker discussed how athletes often struggle in morning or evening sessions depending on their chronotype. Dr. Mah has seen coaches shift an athlete's training from early morning to late morning/early afternoon with positive results. She recommends chronotype assessments (e.g., MEQ) for all athletes. For teams, it's harder but still valuable to tailor schedules. Walker added that disambiguating circadian rhythm from chronotype is an 'aha moment' for many athletes, explaining why they perform better at certain times.