The Fitness Scientist: "Even A Little Alcohol Is Hurting Your Health!" Kristen Holmes

The Fitness Scientist: "Even A Little Alcohol Is Hurting Your Health!" Kristen Holmes


  • Sleep and recovery are improved when people have sex before sleep.
  • Circadian rhythm affects health, and shift workers are at higher risk for various diseases.

Why do you do the work you do?

  • Kristen Holmes is passionate about human flourishing and understanding physiology and psychology to help people improve their health.

What your work is and involves

  • Kristen Holmes is the vice president of performance science at Woop, a technology company focused on human performance.
  • She focuses on understanding markers for tracking health and behaviors for promoting health.

The Importance Of Sleep Wake Timing - circadian rhythm

  • Consistent sleep-wake timing leads to higher levels of positive psychological functioning.
  • Circadian rhythm is the physical, mental, and behavioral changes that happen in a 24-hour cycle.
  • Circadian disruption from irregular sleep-wake patterns increases the risk of cancer, metabolic disease, cardiovascular disease, infertility, and mental health issues.

Humans Haven't Adapted For Artificial Light

  • Exposure to blue light after dark has a pro-depressive effect and impacts the dopamine system.
  • Modern access to constant light has negative consequences as humans have not adapted to artificial light.
  • People have evolved to sleep and wake up in alignment with the natural light-dark cycle.


  • Our relationship with light directly influences our health trajectory.
  • Circadian rhythm and sleep-wake timing play a vital role in promoting health.

The Myths Around Sleep

  • Sleep regularity predicts all-cause mortality independently of sleep duration.
  • Variability in sleep onset and offset times can impact markers of recovery and heart rate variability.
  • Reduced circulating melatonin due to unstable sleep patterns can lead to inflammation and vulnerability to diseases.

Impact of Lack of Sleep

  • Lack of sleep can reduce the release of human growth hormone, impacting physical restoration and regeneration.
  • Consistently getting decent sleep and stabilizing sleep wake time is important for recovery and restoration after physical activities.

Preventive Effect of Sleep Pattern

  • Stabilizing sleep wake time can predict GPA and other performance metrics, benefiting high performers like athletes.
  • Maintaining a consistent sleep wake pattern has prevented sickness for the speaker since 2017.
  • Stabilizing wake-up time is crucial, even if going to bed at the same time is not possible, and can help set the circadian rhythm.

Managing Shifts in Sleep Patterns

  • Parents and those caring for sick family members may have periods of disrupted sleep patterns.
  • Dialing in the feeding window can help mitigate some negative effects of disrupted sleep patterns.

The Best Times To Eat For The Perfect Sleep

  • Time restricted feeding and eating refer to the timing of meals in relation to the light-dark cycle.
  • Eating within an 8 to 12 hour window can lead to better metabolic outcomes and improved sleep.
  • Eating earlier in the day primes the body to utilize nutrients, while consolidating the eating window to 8 to 10 hours can improve metabolic health.
  • Stopping eating 2 to 3 hours before sleep improves sleep and recovery, as it allows resources to be allocated to sleep rather than digestion.
  • Meal timing significantly impacts sleep, and alcohol and meal timing are the two biggest disruptors of a good night's sleep.

The Positive and Negative Effect Of Exercise On Our Sleep

  • Exercising close to bedtime can result in feeling more energized due to adrenaline and cortisol levels, which take time to return to normal.
  • Light exposure during exercise, particularly in well-lit gyms, can contribute to feeling more activated, signaling the body to be awake.

The Importance Of Getting Sunlight When We Wake Up

  • Getting exposure to natural light, ideally 100,000 lux within 5 to 20 minutes of waking up, signals to the body that it's time to be awake.
  • Mimicking daylight and minimizing artificial light exposure before bed helps to protect melatonin release and promote better sleep.

Things To Do For A Perfect Night's Sleep

  • Sleep masks are beneficial to block out even minor sources of light, as any artificial light can impair the ability to enter deeper stages of sleep.
  • To optimize sleep, the environment should be cold, dark, and quiet, with a stable sleep-wake time and a few hours gap between eating and bedtime.
  • Managing stress throughout the day, aligning behaviors with values, and proactively addressing negative stress can contribute to better and more natural sleep.

A Message For People That Aren’t Taking This Information Seriously (00:39:20)

  • Seeking to convey a compelling message to individuals struggling to make healthy choices
  • Emphasizing the importance of understanding personal values and aligning behaviors with them
  • Suggesting the need to identify desired outcomes and make necessary changes, including shedding unsupportive relationships

Growing Up With Addiction (00:45:14)

  • Sharing personal experiences of growing up with a parent battling addiction
  • Describing feelings of deprioritization and the need for independence
  • Reflecting on the impact of a lack of emotional attachments and the importance of addressing related issues as an adult

What Alcohol Is REALLY Doing To Our Sleep

  • Alcohol can disrupt sleep onset and lead to sleep fragmentation.
  • It reduces melatonin production, impacting sleep quality and circadian rhythms.
  • Even small amounts of alcohol can decrease heart rate variability and next-day recovery.
  • Moderate alcohol consumption can have negative health implications.

The Effects Of Coffee On Our Sleep

  • Caffeine, especially when consumed within 8-12 hours of bedtime, can disrupt sleep onset and quality.

Shift Workers Have A Lower Life Expectancy

  • Shift workers, such as healthcare professionals, face a significant reduction in life expectancy and health risks.
  • Strategies like time-restricted eating, controlled light exposure, and managing stress may help mitigate the negative effects of shift work.

Mental Health

  • Social jet lag, characterized by variability in weekday and weekend sleep schedules, is linked to increased non-suicidal ideation.
  • Shift workers, with random sleep-wake times, may be more vulnerable to mental health issues due to circadian disruption and stress management.

How To Reduce Stress In The Moment

  • Taking 30 seconds to do the physiological sigh helps reduce anxiety and stress in the moment.
  • Physiological sigh involves a double inhale followed by an extended exhale.

Sleep Deprivation & How It Affects Our Actions

  • Every 45 minutes of sleep deprivation results in a 5 to 10% decrease in next day mental control and executive function.
  • The relationship between sleep debt and performance metrics like executive function and psychological safety, especially for business executives, is significant.
  • Sleep debt leads to a decrease in psychological safety among direct reports of leaders, impacting team performance.
  • Greater sleep debt leads to an increased risk of accidents, injuries, and a decline in decision-making abilities.

The Relationship Between Sex & Sleep

  • Sex with a partner before bed leads to better markers of sleep and recovery.
  • Masturbation does not have significant effects on markers of sleep and recovery.
  • Ejaculation releases oxytocin, which can have a calming effect and aid in falling asleep.


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What Is HRV & Why Is It So Important?

  • HRV stands for heart rate variability
  • It is a measure of the time interval between heartbeats and indicates the body's ability to adapt to environmental stress
  • A higher heart rate variability indicates better adaptation to stress
  • Heart rate variability is variable and impacted by genetics, gender, biological sex, and age
  • Higher heart rate variability is generally better and correlates with better overall health

Why The Relationship We Have With Ourselves Is So Important To Our Sleep - The Psychological Effects

  • HRV is linked to immunity and psychological well-being
  • Expressing gratitude and maintaining a growth mindset can positively impact psychological functioning and overall well-being
  • Believing in the potential for growth and feeling optimistic about the future is associated with a more positive impact on one's health and physiological markers

The Importance Of A Growth Mindset & Positivity

  • The idea of a growth mindset can counteract stress and enhance productivity
  • Factors such as physiological health, stress management, and purpose can influence mindset
  • There is a two-way link between actions and feelings, and focusing on actions can influence feelings

What To Do If You Have A Motivation Problem

  • Understanding how to produce energy is crucial for motivation
  • Appraisal and perception influence energy production and motivation
  • Helping individuals understand their personal reasons for showing up every day can increase motivation
  • Creating a challenging environment can make individuals excited about their work
  • Breaking out of a downward reinforcing spiral starts with making one different decision

Writing Down Your Values

  • Regularly revisiting and writing down personal values is important
  • Values such as growth, impact, tolerance, compassion, and presence can guide decision-making
  • Understanding how values look in action helps in practicing these behaviors
  • Living one's values is more important than achieving specific goals
  • Focusing on living values leads to consistent performance and personal growth

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