FoundMyFitness · 2025-10-06 · Rhonda Patrick (host), Michael Grandner

Why You Can’t Sleep (and How to Fix It) | Dr. Michael Grandner

108 research-tied claims examined: 2 contradicted 5 overstated 9 context 78 supported 1 corroborated online 13 unverified

Overstated

2:16:05 Michael Grandneroverstatedmoderate

Shift work is a known carcinogen and increases the risk of developing diabetes and dementia.

"shift work in general car- known carcinogenic. It increases diabetes risk, increases dementia risk. Like shift shift work isn't good." (said at 2:16:05)

The claim bundles three assertions. First, shift work is not classified as a 'known carcinogen' (IARC Group 1); rather, the International Agency for Research on Cancer (IARC) classified night shift work as 'probably carcinogenic to humans' (Group 2A) due to limited epidemiological evidence in humans alongside sufficient animal and mechanistic evidence. Second, large observational cohorts and meta-analyses support an increased risk of type 2 diabetes among shift workers (e.g., pooled hazard ratio ~1.30). Third, meta-analyses of observational studies demonstrate a modest but statistically significant positive association between shift work and the risk of dementia (pooled hazard ratio ~1.13). Because shift work is a probable rather than a confirmed/known carcinogen, the overall statement is overstated.

partial: Shift work and health outcomes: an umbrella review of systematic reviews and meta-analyses… (Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine 2022) · cited 81x in the literature
"We observed highly suggestive evidence for associations between shift work and myocardial infarction (having ever vs having never done shift work) and diabetes mellitus incidence (per 5-year increment in shift work)... Two health outcomes, including prostate cancer incidence (having ever vs having never done shift work and rotating night shift work vs daytime work) and colorectal cancer incidence (longest vs shortest shift work time), were only supported by weak evidence." (abstract, results, passage verified)
pubmed full study (doi)
supports: Shift work is significantly and positively associated with dementia: A meta-analysis study… (Frontiers in public health 2023) · cited 18x in the literature
"A random-effects model showed a modest association between shift work and an increase in dementia cases (pooled hazard ratio = 1.13; 95% confidence interval: 1.04-1.23; p = 0.04)." (abstract, results, passage verified)
pubmed full study (doi)
supports: Association between night shift work and the risk of type 2 diabetes mellitus: a cohort-ba… (BMC endocrine disorders 2024) · cited 25x in the literature
"Overall, night shift workers exhibited a 30% increased incidence of T2DM compared to their daytime counterparts (HR = 1.30, 95% CI: [1.18, 1.43], P < 0.001)." (abstract, results, passage verified)
pubmed full study (doi)

2:19:05 Michael Grandneroverstatedmoderate

In sleep-deprived individuals, a daytime nap significantly improves metabolism and muscle strength.

"there's data that shows like even in sleep-deprived people, a decent nap in the middle of the day can dramatically improve metabolism, muscle strength, all this stuff." (said at 2:19:05)

A meta-analysis of randomized controlled trials (PMID: 36690376) indicates that a daytime nap (30 to <60 minutes) provides moderate-to-large improvements in physical and cognitive performance (standardized mean difference = 0.99 for physical performance) and reduces perceived fatigue following normal sleep or partial sleep deprivation in athletic and active cohorts. However, characterizing this as a 'dramatic' improvement in both muscle strength and systemic metabolism overstates the magnitude and scope of the evidence; napping primarily acts as an acute restorative countermeasure to temporary performance deficits rather than substantially altering underlying metabolic function.

partial: Is daytime napping an effective strategy to improve sport-related cognitive and physical p… (British journal of sports medicine 2023) · cited 52x in the literature
"When performed after a normal night of sleep, napping from 12:30 hours to 16:50 hours (with 14:00 hours being the most frequent time) improved cognitive (SMD=0.69, 95% CI: 0.37 to 1.00; I 2 =71.5%) and physical performance (SMD=0.99, 95% CI: 0.67 to 1.31; I 2 =89.1%) and reduced the perception of fatigue (SMD=-0.76, 95% CI: -1.24 to -0.28; I 2 =89.5%). The positive effects of napping were also confirmed after partial sleep deprivation." (abstract, results, passage verified)
pubmed full study (doi)

5:07:50 Michael Grandneroverstatedlow

A comprehensive literature review led by Teresa Arora found that improving sleep consistently leads to improvements in physical and emotional resilience across studies.

"A colleague of mine, Teresa Arora, she led this project that I also helped on. We looked at... We basically scoured the entire medical literature on resilience and sleep... And basically what we found was across the board, people... If you can sleep better, your resilience will improve." (said at 5:07:50)

A 2022 systematic review and meta-analysis led by Teresa Arora (PMID 35462348) examined the relationship between sleep duration/quality and resilience across 68 studies in non-clinical populations. The meta-analysis identified a weak positive correlation between sleep duration and resilience (r = 0.11) and a modest correlation with sleep quality (r = 0.27; attenuated to r = 0.18 in prospective studies), alongside evidence of significant publication bias. The authors noted that the literature is predominantly observational and cross-sectional, concluding that additional prospective and interventional research is needed to verify whether improving sleep directly improves resilience.

partial: A systematic review and meta-analysis to assess the relationship between sleep duration/qu… (Sleep medicine reviews 2022) · cited 103x in the literature
"Pooled results indicated a weak, positive correlation between sleep duration and resilience (r = 0.11, p < 0.001), and sleep quality (r = 0.27, p < 0.001). The pooled correlation was slightly attenuated for prospective studies pertaining to sleep quality and resilience (r = 0.18, p < 0.001). We found evidence of high publication bias for studies that explored the relationship between sleep quality and resilience. Sleep and resilience are positively correlated but additional research is needed to verify the direct relationship through carefully designed, prospective studies that capture both subjective and objective sleep estimates." (abstract, results and conclusions, passage verified)
pubmed full study (doi)

5:27:19 Michael Grandneroverstatedlow

Sleeping with a pet or other animal in the bedroom increases sleep fragmentation.

"Anyone who has an animal in their room, another mammal in their room moving around... You're going to have more fragmented sleep." (said at 5:27:19)

While objective actigraphy studies confirm that an animal's nighttime movements can trigger awakenings or movement transitions in humans—particularly when sharing the same bed—the claim that having an animal anywhere in the room universally fragments sleep is overstated. An actigraphy study of 40 adults found that having a single dog in the bedroom did not significantly impair sleep efficiency, whereas having the dog directly on the bed did reduce sleep efficiency. Other observational studies show that while bed-sharing and owning multiple pets are associated with poorer objective sleep parameters and subjective sleep quality, having a pet simply present in the bedroom does not consistently cause sleep disruption.

partial: The Effect of Dogs on Human Sleep in the Home Sleep Environment. (Mayo Clinic proceedings 2017) · cited 43x in the literature
"Human sleep efficiency was lower if the dog was on the bed as opposed to simply in the room (P=.003). Humans with a single dog in their bedroom maintained good sleep efficiency; however, the dog's position on/off the bed made a difference. A dog's presence in the bedroom may not be disruptive to human sleep, as was previously suspected." (abstract, results and conclusions, passage verified)
pubmed full study (doi)
supports: Human-Animal Co-Sleeping: An Actigraphy-Based Assessment of Dogs' Impacts on Women's Night… (Animals : an open access journal from MDPI 2020) · cited 25x in the literature
"We found a significant positive relationship between human and dog movement over sleep periods, with dogs influencing human movement more than humans influenced dog movement. Dog movement accompanied approximately 50% of human movement observations, and dog movement tripled the likelihood of the human transitioning from a non-moving state to a moving state." (abstract, results, passage verified)
pubmed full study (doi)
context: The effects of bed sharing on sleep: From partners to pets. (Sleep health 2021) · cited 61x in the literature
"We found that, across dyad types, in general, subjective reports of sleep quality were better when bed sharing despite generally worse objective measures of sleep." (abstract, results, passage verified)
pubmed full study (doi)

3:33:02 Michael Grandneroverstatedmoderate

Untreated sleep apnea is a leading cause of frequent nocturnal urination.

"Untreated sleep apnea is probably the leading cause of nocturnal frequent urination, because you keep having these arousals at night and your bladder is like, "Okay, while you're awake, might as well."" (said at 3:33:02)

Untreated obstructive sleep apnea (OSA) is a well-recognized, frequent contributor to nocturia (nocturnal frequent urination), and CPAP therapy often improves or resolves these symptoms. However, designating it as 'probably the leading cause' is overstated; nocturia is a multifactorial condition with several leading causes, including lower urinary tract dysfunction (such as benign prostatic hyperplasia and overactive bladder), cardiovascular disease, nocturnal polyuria from aging or diabetes, and diuretic use. Furthermore, the physiological driver in OSA is not merely waking up and deciding to void, but primarily inspiratory efforts against an occluded airway creating negative intrathoracic pressure, cardiac distension, and elevated release of atrial natriuretic peptide (ANP), which directly induces nocturnal polyuria.

partial: Sleep disordered breathing and nocturnal polyuria: nocturia and enuresis. (Sleep medicine reviews 2003) · cited 133x in the literature
"The nocturnal polyuria of sleep apnea is an evoked response to conditions of negative intrathoracic pressure due to inspiratory effort posed against a closed airway. The mechanism for this natriuretic response is the release of atrial natriuretic peptide due to cardiac distension caused by the negative pressure environment." (abstract, results, passage verified)
pubmed full study (doi)
partial: Nocturia and obstructive sleep apnoea. (Nature reviews. Urology 2024) · cited 11x in the literature
"Nocturia, the need to urinate at night, is a common symptom in patients with obstructive sleep apnoea (OSA). Continuous positive airway pressure treatment can reduce nocturia in some patients, but the underlying mechanisms are complex and not fully understood." (abstract, results, passage verified)
pubmed full study (doi)

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.