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#48 – Matthew Walker, Ph.D., on sleep – Part II of III: Heart disease, cancer, sexual function, and the causes of sleep disruption (and tips to correct it)

Apr 8, 2019 2h 4m 18 insights
<p>In part 2 of this 3 part series, Matthew Walker, professor of neuroscience at UC Berkeley and expert on sleep, describes the preponderance of evidence linking poor sleep to cardiovascular disease, cancer, and sexual function. He also details the impact of cortisol on our nervous system contributing to sleep disturbances and insomnia as well as the efficacy and risks associated with the most common sleeping pills. Matthew also describes the sleep needs of teenagers and urgently lays the case that we should reconsider school start times. We also get into the effect of electronics at night, the efficacy of napping, the general impact of modern society on our sleep habits, and what changes we can make to course correct. </p> <p>We discuss:</p> <ul> <li>Sleep and cardiovascular disease [6:00];</li> <li>Fuel partitioning and dieting while sleep deprived [16:45];</li> <li>Sleep and the reproductive function: testosterone, sperm count, FSH, menstrual cycles, and fertility [19:45];</li> <li>The biological necessity of sleep, the lack of a "safety net", sleep debt, and ways to course correct sleep problems [23:45];</li> <li>Fighting cancer and improving immune function with sleep [34:30];</li> <li>The medical profession: A culture that devalues sleep [47:30];</li> <li>The sleep needs of children, the travesty of early school start times, electronics at night, and advice for parents [1:04:45];</li> <li>How exposure to light affects sleep, and how modern society has changed our sleep habits  [1:26:15];</li> <li>Is napping helpful? [1:36:00];</li> <li>The effect of cortisol levels on sleep [1:41:15];</li> <li>Are sleeping pills doing more harm than good? [1:52:15]; and</li> <li>More.</li> </ul> <p><span style="white-space: pre-wrap;">Learn more at <a href="http://www.peterattiamd.com/">www.PeterAttiaMD.com</a><br /> Connect with Peter on <a href="Facebook.com/PeterAttiaMD">Facebook</a> | <a href="Twitter.com/PeterAttiaMD">Twitter</a> | <a href="Instagram.com/PeterAttiaMD">Instagram</a>.<br /></span></p>
Actionable Insights

1. Prioritize Sleep for Heart Health

Aim for adequate sleep, ideally 7+ hours, as insufficient sleep (5 hours or less) significantly increases the risk of heart attacks and coronary artery calcification, while elevating detrimental stress hormones and blood pressure.

2. Optimize Sleep for Fat Loss

Ensure sufficient sleep (more than 6 hours) when trying to lose weight, as undersleeping causes 70% of weight loss to come from lean muscle mass instead of fat, and impairs metabolic efficiency leading to hyperinsulinemia and increased junk food cravings.

3. Boost Immunity with Sleep

Prioritize adequate sleep to strengthen your immune system and reduce cancer risk; one night of only four hours of sleep can decrease natural killer cell activity by 70%, increasing vulnerability to cancer development and growth.

4. Improve Sleep for Fertility

For optimal reproductive function, men and women should aim for adequate sleep, as insufficient sleep (5-6 hours) can age a man’s testosterone levels by a decade and reduce sperm quality, while in women it can reduce FSH and increase abnormal menstrual cycles.

5. Enhance Decision Making with Sleep

Ensure sufficient sleep to improve cognitive function and decision-making, as even one hour of lost sleep can lead to increased car accidents, suicidal attempts, and impaired judgment, with effects lasting up to three days.

6. Avoid Sedative Sleep Aids

Do not use sedative-hypnotic sleep medications like Ambien, as they induce sedation rather than naturalistic, restorative sleep, are associated with higher risks of death and cancer, and can actually weaken brain connections and memory formation.

7. Reduce Nighttime Stress

Implement behavioral strategies to lower high nighttime cortisol and sympathetic nervous system activity, such as separating stressful activities (e.g., email) from bedtime and practicing meditation to promote a parasympathetic-dominant state.

8. Control Light for Better Sleep

Maximize darkness in your sleeping environment and use warm, yellow, low-wattage light (avoiding cold blue LED light) in the evening, as darkness is crucial for natural melatonin release, while blue light significantly suppresses it.

9. Optimize Bedroom for Sleep

Use your bed exclusively for sleep and intimacy to establish a strong mental association; if you struggle to fall asleep, get out of bed after 20 minutes, go to another room in dim light, and only return when truly sleepy.

10. Limit Screens Before Bed

Avoid using screens like iPads for at least an hour before bed, and ideally remove all technology from the bedroom, as screen light disrupts melatonin, reduces REM sleep, and contributes to sleep procrastination and anticipatory anxiety.

11. Manage Caffeine Intake

Be mindful of caffeine consumption, especially later in the day, to allow the natural buildup of adenosine, the “sleepiness chemical,” which is essential for falling and staying asleep soundly.

12. Avoid Naps for Insomnia

If you experience difficulty falling or staying asleep at night, avoid napping during the day, particularly in the late afternoon, as naps reduce the healthy sleepiness (adenosine) needed for sound nighttime sleep.

13. Strategic Napping for Performance

If you don’t have nighttime sleep issues, strategic naps can provide benefits for learning, memory, immune function, and cardiovascular health; a 90-minute nap allows the brain to complete a full sleep cycle.

14. Advocate for Later School Start Times

Support initiatives to delay school start times, ideally to 9 AM or 10 AM, as early starts lead to chronic sleep debt in teenagers, impairing academic performance, increasing behavioral problems, and significantly raising car accident rates.

15. Understand Teen Sleep Needs

Parents should recognize that teenagers biologically require 9-10 hours of sleep and naturally have a later circadian rhythm, so avoid chastising them for sleeping in on weekends, as they are often recovering from chronic sleep debt.

16. Remove Teen Devices from Bedroom

Encourage teenagers to remove phones and social media devices from their bedrooms, as over 80% wake up to check them, causing alertness spikes, dependency, and “fear of missing out” (FOMO) that directly relates to insufficient sleep.

17. Minimize Circadian Rhythm Disruption

Be cautious with frequent large time zone changes (e.g., “social jet lag”) and for severe, chronic circadian disruption, seek a sleep specialist who can use tools like reverse melatonin, blue light therapy, and environmental light exposure.

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