Source: Podcast Peter Attia with Matthew Walker #1

Stages of Sleep

Humans (Mammals) have 2 stages:

  1. Non-REM
  2. REM

Non-REM has 4 stages: Cleverly titled=Stages 1, 2, 3, and 4

  • Stages 3 and 4 are the very deep restorative stages
  • Stages 1 and 2 are the lightest stages of sleep

REM sleep: (REM=Rapid eye movement, based on the bizarre horizontal shifting eye movements)

90 minute sleep cycles

  • Every 90 minutes, your brain cycles between non-REM and REM sleep
  • Then this is replayed every 90 minutes to create what we call a standard cycling architecture of sleep, or what we call a hypnogram of sleep

Functions of different stages of sleep

Deep non-REM sleep (stage 3 and 4)

  • Protects new learning from the day before
  • “You need sleep after learning to essentially hit the save button on new memories so that you don’t forget.”

Stage 2 of non-REM

  • Refreshes and prepares your brain for future learning and memory
  • Sleep spindles exponentially increase towards the end of the night, so you get most of your sleep spindle-rich sleep in the last two hours of the night
  • So the stage 2 non-REM sleep happens mostly in the second half of night and prepares your brain to learn
  • “The more of those sleep spindles that you have, the greater refreshment of your memory and coding ability.”

What’s the biggest detriment that persons face clinically with the reduction of REM?

Importance of REM sleep ⇒ We need to worry about both deep and REM sleep, but REM is arguably even more important (and alcohol affects REM sleep)

Sleep gets worse as we age, and therefore our immune system gets worse

“One of the most dramatic changes with age, and the most sizable and robust physiological changes with age that we see, is that your sleep gets worse. And sleep is probably one of the most powerful regulators of your immune system.”

– Matthew Walker

Technological Devices

⇒ Biological reasons to avoid electronics…

  • This study suggests using an iPad before bed has negative effect on sleep ⇒ 50% drop in melatonin (aka you lose 50% signal of sleep timing), and your peak melatonin will arrive 3 ”
  • iPad time also reduces REM time
  • Effects last 2-3 days
  • Television ⇒ TV doesn’t have quite the same effect, but… it does make brain associate bedroom with TV and “when you start to form those maladaptive associations, it can be a trigger of insomnia and anxiety.

⇒ The mental component…

  • I think this component may be . . . stronger than the biological component
  • Sleep procrastination: Devices can cause sleep procrastination (Since it’s there, I’ll check email or FB one more time)
  • Dependency causing an alertness spike: Surveys suggest many kids wake up during night to check phones to check phones or social media
    • Dependency causing an alertness spike

⇒ Anticipatory anxiety:

  • Devices and technologies cause what’s called anticipatory anxiety
  • Most people, the first thing that they do when they wake up in the morning unlock this world of anxiety that comes flooding in through their phone (Emails, texts, social media, etc.)
  • You essentially are training your brain to anticipate that wave of anxiety every morning
  • That anticipatory expectation in the morning lessens the amount of deep sleep that you get
  • You end up sleeping in a shallow state, and you don’t get the same amount of deep sleep
  • And the greater the anxiety that there is coming in the next morning, the greater the reduction in deep sleep that you have the night before

Tools to get better sleep

“There is a whole arsenal of tools in the sleep doc kind of box that we can use, to sort of make these manipulations, either be it for people with insomnia, be it people with anxiety, be it people with jet lag, or what’s called circadian phase delay.”

  • Exogenous agents like melatonin
  • Blue light
  • Regular exercise
  • Exposure to daylight
  • Manipulations of body temperature

Souce: Podcast of Petter Attia and Matthew Walker #2

Sleep and Appetite

Sleep and appetite regulation

  • This paper shows that subjects limited to 4-6 hours of sleep per night for 1 week will have:
    • Downregulated leptin (the satiety hormone that signals to your brain that you are full and don’t need to eat anymore) is turned down
    • Upregulated ghrelin (a hunger hormone signaling the body to eat more) is ramped up
  • People sleeping 6 hours a night will eat extra calories during the next day

Sleep and Metabolism

Sleep is paramount for metabolic health. 

Studies have shown that when you sleep 5.5 hours per night instead of 8.5 hours per night, a lower proportion of the energy you burn comes from fat, while more comes from carbohydrate and protein. This can predispose you to fat gain and muscle loss. Additionally, insufficient sleep or abnormal sleep cycles can lead to insulin insensitivity and metabolic syndrome, increasing your risk of diabetes and heart disease.

There are two important parts of the sleep-wake cycle:

  1. Slow wave sleep (also known as deep sleep)
  2. REM sleep (REM stands for Rapid Eye Movement)

During slow wave sleep the body relaxes, breathing becomes more regular, blood pressure falls, and the brain becomes less responsive to external stimuli, which makes it more difficult to wake up. This phase is critical for renewal and repair of the body. During slow wave sleep, the pituitary gland releases growth hormone, which stimulates tissue growth and muscle repair. Researchers also believe that the body’s immune system is repaired during this stage. Slow wave sleep is particularly critical if you’re an athlete.

REM sleep is to the mind what slow wave sleep is to the body. The brain is relatively quiet during most sleep phases, but during REM your brain comes to life. REM sleep is when your brain dreams and re-organizes information. During this phase your brain clears out irrelevant information, boosts your memory by connecting the experiences of the last 24 hours to your previous experiences, and facilitates learning and neural growth. Your body temperature rises, your blood pressure increases, and your heart rate speeds up. Despite all of this activity, your body hardly moves. Typically, the REM phase occurs in short bursts about 3 to 5 times per night.

Slow wave sleep helps you recover physically while REM sleep helps you recover mentally.

Source: James Clear on Sleep

Sleep and Alcohol

  • But alcohol does 3 things to sleep:
    • 1) it’s a sedative so works like sleeping pills… you might lose consciousness more quickly, but you’re not “falling asleep” faster
    • 2) alcohol fragments sleep so you wake up many more times during the night; often so brief that you don’t remember but they have an impact on your physiology
    • 3) alcohol blocks REM sleep, so you wake up unrefreshed and unrestored

Alcohol’s impact on Peter Attia Oura Ring readings:

  • Resting heart rate 6-8 beats higher
  • Heart rate variability is compressed by 20%
  • Respiratory rate is increased by 2 breaths/minute
  • Body temperature up by .3-.6 degrees

⇒ This is bad news for people who enjoy a night cap

  • You need your heart rate to decrease
  • You need to drop your core body temp by 2-3 degrees F to initiate sleep
  • But alcohol raises your core body temperature, so you get more fragmented sleep, more awakenings, and you disrupt REM sleep
  • “On every one of those levels, that’s exactly what we see in a scientific evidence.”

⇒ Alcohol makes you have to pee more in the night

  • Alcohol inhibits vasopressin
  • So you urinate disproportionately more than you’re consuming because it inhibits an anti-diuretic hormone

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