Huberman Lab · 2026-01-05 · Andrew Huberman (host), James Clear

Best Ways to Build Better Habits & Break Bad Ones | James Clear

21 research-tied claims examined: 11 supported 3 needs context 1 contradicted 3 overstated 3 unverified

1 Contradicted by research
0:25:00Andrew Huberman (host)contradictedmoderate

The critical period for robust passive developmental neuroplasticity (such as learning multiple languages without an accent) typically closes around age 25.

"and uh it's very robust up until they always say till age 25, but about that is when the window closes for like multi-language learning without accents, you know, becomes much much more difficult after 15, 20, 25 than it does say at 40, 45 or 60." (said at 0:25:00)

The claim misidentifies the timing of the critical/sensitive period for language acquisition and accent-free speech. In developmental neuroscience and psycholinguistics, the critical or sensitive period for acquiring a language natively without an accent and with native-like grammar closes much earlier—typically around early childhood to puberty (roughly ages 5 to 12)—not at age 25. While general prefrontal cortical maturation continues into the mid-20s, the capacity for effortless, passive phonological and grammatical language acquisition declines significantly around puberty.

3 Overstated
0:41:45Andrew Huberman (host)overstatedmoderate

The brain learns and undergoes neuroplastic changes primarily through friction and failure rather than through successful performance.

"This is how the brain learns. The brain learns by experiencing friction. It doesn't learn by experiencing performance. I mean, we don't learn from performance. We only learn from failure, right? That the brain won't change unless it has to change." (said at 0:41:45)

The claim overstates the primacy of errors and failure in learning. While sensory prediction errors and discrepancy detection are well-established drivers of rapid adaptation (particularly in cerebellar circuits), the brain equally relies on reward-based reinforcement learning, dopaminergic signaling, and use-dependent plasticity to consolidate and retain successful behaviors. Both error processing and successful performance are complementary, essential components of neuroplasticity and skill acquisition rather than failure operating as the primary mechanism over success.

1:14:55Andrew Huberman (host)overstatedmoderate

In order to wake up feeling refreshed and energized, human body temperature must increase by approximately 1 to 3 degrees Fahrenheit.

"And in order to wake up feeling refreshed and energized, your body temperature actually has to increase by about 1 to 3°." (said at 1:14:55)

Core body temperature follows an endogenous circadian rhythm where the lowest point (nadir) occurs during the second half of the nocturnal sleep period, after which temperature begins to rise leading into morning awakening and daytime alertness. However, claiming that body temperature must rise by '1 to 3 degrees Fahrenheit' to wake up refreshed overstates the magnitude: the entire 24-hour peak-to-trough circadian amplitude of human core body temperature is typically only about 0.5 °C to 1.0 °C (~0.9 °F to 1.8 °F), and only a portion of that change occurs immediately around waking.

1:41:50Andrew Huberman (host)overstatedmoderate

Acute exercise causes circulating cortisol levels to increase by at least fourfold during and after a workout.

"when you exercise, and you probably quadruple your cortisol levels at least during the workout and and afterwards, depending on the workout." (said at 1:41:50)

While moderate-to-high intensity acute exercise stimulates the hypothalamic-pituitary-adrenal axis and increases circulating cortisol, the magnitude and consistency of the response are substantially overstated. Controlled exercise trials demonstrate that cortisol elevations are intensity-dependent, generally occurring above ~60% of VO2max. At high intensities (such as 80% VO2max), cortisol typically increases by approximately 40% to 83% (less than a 2-fold increase), far below the claimed 'at least fourfold' (400%) increase. Furthermore, low-intensity exercise produces minimal changes or even slight decreases in circulating cortisol after adjusting for plasma volume and circadian rhythms, and levels typically return to or drop below baseline within a few hours post-exercise.

3 Needs context
0:10:39Andrew Huberman (host)needs contextmoderate

Large glucose peaks and valleys lead to brain fog, fatigue, irritability, and hunger.

"In fact, large glucose peaks and valleys lead to brain fog, fatigue, irritability, and hunger." (said at 0:10:39)

Evidence supports a link between postprandial glucose dynamics (particularly postprandial dips below baseline) and increased hunger and caloric intake in healthy individuals. However, evidence linking typical daily glycemic excursions directly to cognitive impairment ('brain fog'), fatigue, and irritability is more mixed and largely observed in individuals with diabetes or during episodes of acute reactive hypoglycemia.

1:02:46Andrew Huberman (host)needs contextlow

Plant foliage reflects near-infrared light that penetrates the human body surface and stimulates mitochondrial function.

"there's a lot of infrared light essentially being reflected back on you. And that infrared light is not the type that damages your skin. It is the type that feeds your mitochondria. It actually penetrates your body surface. It literally charges the mitochondria." (said at 1:02:46)

The claim combines three established optical and biological principles, but extrapolates them into an unproven physiological effect under natural conditions. In botany and remote sensing, healthy plant foliage strongly reflects near-infrared (NIR) light (the 'red edge' phenomenon). In photobiology and medicine, NIR light (760–1400 nm) penetrates human skin into subcutaneous tissue and stimulates mitochondrial chromophores (such as cytochrome c oxidase) through photobiomodulation (PBM). However, while sunlight and NIR irradiation have demonstrated biological and mitochondrial effects, evidence specifically demonstrating that the ambient irradiance reflected from foliage is sufficient to elicit meaningful mitochondrial stimulation in humans is theoretical and lacks direct clinical verification.

1:41:07Andrew Huberman (host)needs contextmoderate

Mental and physical performance peaks approximately 3 hours and 11 hours after waking, driven by diurnal variations in body temperature and circulation.

"3 hours after waking or 11 hours after waking seem to be ideal times to— mentally and physically we, uh, probably due to changes in body temperature and circulation of the, you know, that morning cortisol rise that wakes people up." (said at 1:41:07)

Diurnal variations in core body temperature and circadian rhythmicity significantly influence both physical and cognitive performance throughout the day. Physical capacity (such as sprint speed, power output, and neuromuscular function) generally peaks in the late afternoon or early evening (roughly 10–12 hours after typical waking), which closely aligns with the peak in core body temperature. Cognitive functions such as attention and mental flexibility often perform well in the mid-to-late morning (several hours post-waking after sleep inertia subsides). However, describing these as universal, rigid peaks at exactly 3 and 11 hours post-waking oversimplifies individual variations driven by chronotype, task-specific cognitive demands, and sleep homeostasis.

11 Supported by research
0:03:35James Clearsupportedmoderate

The most common New Year's resolution is to do some form of exercise.

"The most common New Year's resolution, for example, is to do some form of exercise." (said at 0:03:35)

A large-scale study investigating free-form New Year's resolutions among the general public found that goals related to physical health (primarily exercise and physical activity), weight loss, and eating habits were the most frequently chosen resolutions, with physical health being the most popular category overall.

0:10:11Andrew Huberman (host)supportedhigh

Glucose is the major fuel for human cells, especially brain cells, and directly affects brain function, mood, and energy levels.

"That's because it is the major fuel for our cells, especially our brain cells. Glucose directly impacts our brain function, mood, and energy levels." (said at 0:10:11)

It is well-established in human physiology and neurobiology that glucose is the primary metabolic fuel for human cells, particularly the brain, which relies heavily on continuous glucose transport across the blood-brain barrier to sustain basal cellular energetics. Fluctuations in glucose metabolism and carbohydrate availability directly influence cognitive performance, stress reactivity, mood regulation, and perceived energy levels.

0:11:08Andrew Huberman (host)supportedmoderate

A brief walk after a meal helps keep blood glucose levels stable.

"Lingo has helped me to better understand what foods to eat, when to eat, and how things like a brief walk after a meal can help keep my glucose stable and much more." (said at 0:11:08)

Meta-analyses of randomized crossover trials demonstrate that light physical activity, such as a brief or light-intensity walk after meal consumption, significantly reduces postprandial glucose excursions and attenuates postprandial glucose and insulin spikes compared to remaining sedentary or prolonged sitting.

0:46:10Andrew Huberman (host)supportedhigh

The gut microbiome consists of trillions of microorganisms lining the digestive tract that influence immune status, metabolic health, and hormone levels.

"The gut microbiome consists of trillions of little microorganisms that line your digestive tract and impact things such as your immune status, your metabolic health, your hormone health, and much more." (said at 0:46:10)

The host's statement accurately summarizes well-established biological facts and broad scientific consensus. The human gastrointestinal tract is colonized by tens of trillions of microorganisms (the gut microbiome) that produce bioactive metabolites (such as short-chain fatty acids and tryptophan catabolites) which actively regulate immune function, metabolic homeostasis (e.g., glucose and lipid metabolism), and endocrine pathways (including thyroid, gut-derived, and steroid hormones).

0:47:20Andrew Huberman (host)supportedmoderate

Red light and near-infrared light improve muscle recovery, skin health, wound healing, acne, pain, inflammation, mitochondrial function, and visual acuity.

"Now, in addition to sunlight, red light and near-infrared light sources have been shown to have positive effects on improving numerous aspects of cellular and organ health, including faster muscle recovery, improved skin health and wound healing, improvements in acne, reduced pain and inflammation, even mitochondrial function, and improving vision itself." (said at 0:47:20)

Photobiomodulation (PBM) using red and near-infrared (NIR) light (wavelengths ~600–1100 nm) has been shown across multiple systematic reviews and meta-analyses to exert biological and clinical benefits across the listed domains. The primary mechanism involves photon absorption by mitochondrial cytochrome c oxidase, which enhances electron transport chain activity, ATP synthesis, and cellular signaling. Systematic reviews of clinical trials confirm that red and NIR light therapy significantly improves muscle recovery (reducing delayed-onset muscle soreness and maintaining performance), accelerates surgical and chronic wound healing, decreases pain, improves dermatological outcomes (including acne vulgaris), and enhances uncorrected visual acuity and myopia control in ophthalmology.

0:50:00Andrew Huberman (host)supportedhigh

Self-testing and post-learning reflection are the most effective study techniques for retaining learned material compared to rereading or highlighting.

"When students, for instance, would read a passage once or twice or three times or four times, and they did all the derivations of do they take notes? Do they highlight? Do they talk about with friends? Etc. There are two things that really make things stick, and one is self-testing. Just, you know, reflecting later like, "Oh, did I what happened? I don't remember that. No, I got that wrong." That that's incredible for self-evaluation in low stakes is is incredibly powerful for retaining information. And the other one was just reflecting on like, what happened?" (said at 0:50:00)

A landmark comprehensive evaluation of 10 learning techniques by Dunlosky et al. (2013) demonstrated that practice testing (self-testing/retrieval practice) and distributed practice provide high utility for long-term retention and generalization across diverse learners and materials. Reflective/elaborative techniques (such as self-explanation and elaborative interrogation) received moderate utility ratings, whereas passive strategies like rereading and highlighting/underlining were rated as having low utility and minimal efficacy for durable learning.

1:14:44Andrew Huberman (host)supportedhigh

In order to fall asleep and stay deeply asleep, human core body temperature must decrease by approximately 1 to 3 degrees Fahrenheit.

"And that's because in order to fall asleep and stay deeply asleep, your body temperature actually has to drop by about 1 to 3°." (said at 1:14:44)

Human sleep onset and non-rapid eye movement (NREM) / slow-wave sleep are tightly coupled to circadian thermoregulation. Core body temperature (CBT) follows a 24-hour sinusoidal rhythm with an amplitude of approximately 0.5 to 1.5 °C (about 1 to 3 °F), reaching its minimum during nocturnal sleep. Sleep initiation is triggered as distal vasodilation dissipates core heat to the periphery, causing the steep decline in CBT and brain temperature necessary for normal sleep architecture and maintenance.

1:20:33Andrew Huberman (host)supportedmoderate

Shift work is associated with adverse health outcomes including gastrointestinal dysfunction, increased cancer risk, and reduced longevity.

"There is a ton of data just showing how bad it is for your health, GI health, cancer risk, longevity, etc., to be a shift worker." (said at 1:20:33)

Substantial epidemiological evidence from systematic reviews and meta-analyses supports the association between shift work (especially rotating or night-shift work) and adverse health outcomes across multiple domains. Meta-analyses demonstrate significantly elevated risks for gastrointestinal disorders (such as gastro-esophageal reflux disease, indigestion, and peptic ulcers), modest increases in cancer risk (such as breast cancer, with dose-response relationships seen with longer duration of exposure), and increased cardiovascular and all-cause mortality.

1:41:21Andrew Huberman (host)supportedlow

A flattened diurnal cortisol curve predisposes individuals to insomnia and anxiety.

"We hear so much about cortisol being a stress hormone, we forget that morning cortisol needs to be very, very, very high in order to have low cortisol at night. If you don't and you have this kind of flat cortisol curve as they call it, sets you up for insomnia, anxiety, a bunch of things that are really bad." (said at 1:41:21)

Observational and longitudinal cohort studies show that a flattened diurnal cortisol slope (DCS) is significantly associated with anxiety symptoms and poorer sleep parameters (such as lower sleep efficiency and shorter total sleep time). In large population-based cohorts (e.g., MIDUS), longitudinal analyses demonstrate bidirectional relationships between anxious arousal and a flatter diurnal cortisol slope.

1:51:24Andrew Huberman (host)supportedmoderate

Consuming leafy greens and supplementing with N-acetylcysteine (NAC) enhances glutathione synthesis and systemic detoxification.

"making an effort to eat more leafy greens and supplementing with NAC, N-acetylcysteine, both of which can support glutathione production and detoxification." (said at 1:51:24)

N-acetylcysteine (NAC) is a well-established cysteine donor and rate-limiting precursor for cellular glutathione (GSH) synthesis, functioning clinically as an antidote in drug toxicity (such as acetaminophen overdose) to restore hepatic GSH pools and facilitate metabolic detoxification. In addition, dietary phytonutrients and vegetables (such as cruciferous and leafy greens) have been shown to upregulate glutathione synthesis and Phase II detoxification pathways, primarily through Nrf2 activation.

1:53:57James Clearsupportedmoderate

Studies demonstrate that establishing a new habit is easier when performed in a novel or clean environment devoid of cues associated with competing behaviors.

"there are some studies that have shown that, uh, or have found that, um, it tends to be easier to build a new behavior when you're in a clean context. When you're in a context where you're not battling the previous cues for your other habits." (said at 1:53:57)

Studies on the habit discontinuity effect and context change demonstrate that habits are strongly tied to recurring environmental cues. When context changes (such as moving to a new environment or eliminating cues linked to existing/competing habits), automatic cue-response patterns are disrupted, rendering behavior more malleable and responsive to intentional goal pursuit and new habit formation.

3 No source found (not proven false)
0:49:00Andrew Huberman (host)unverifiedvery low

Scientific studies show that reflecting on information after an activity leads to faster learning and longer memory retention.

"there's this interesting, um, shift in the literature in the last couple of years, which clearly shows that anything that we reflect on later, we learn faster and we retain longer." (said at 0:49:00)

No specific scientific publications directly evaluating the claim that post-activity reflection leads to faster learning and longer memory retention were fetched and verified within the search parameters. While related cognitive concepts such as retrieval practice, post-learning consolidation, and reflective practice are widely discussed in cognitive science and education literature, the specific claim remains unverified in this search. This verdict does not prove the claim false, but indicates that specific supporting records were not located or retrieved.

1:37:01Andrew Huberman (host)unverifiedvery low

Waking up in the morning, including waking immediately prior to a scheduled alarm, is triggered by a circadian rise in cortisol reaching a specific threshold.

"It's cuz cortisol rose to a certain threshold a minute before your normal alarm clock time, or even if you told yourself the night before, "Got to get up at 7:30," goes off 7:29, like you're clocking it in sleep, believe it or not." (said at 1:37:01)

No eligible publications could be retrieved within the search budget to verify the claim. While research has described circadian variations in hypothalamic-pituitary-adrenal (HPA) axis activity and anticipatory adrenocorticotropic hormone (ACTH) surges prior to expected awakening times (e.g., Born et al., 1999), specific evidence demonstrating that spontaneous or pre-alarm awakening is triggered by cortisol reaching a distinct threshold was not retrieved.

2:08:21Andrew Huberman (host)unverifiedlow

Many individuals clinically classified as obese report in research surveys that they avoid exercising because they perceive taking time to exercise as selfish or self-indulgent.

"Years ago I read something that many [clears throat] people—I don't know if this is true, but this article claimed that many people who are obese, like meet the clinical definition of obese, self-reported that they didn't want to exercise because they felt it made them feel selfish." (said at 2:08:21)

A systematic search of PubMed and Europe PMC failed to identify research surveys or clinical studies demonstrating that individuals clinically classified as obese commonly report avoiding exercise because they view taking time to exercise as 'selfish' or 'self-indulgent'. While qualitative studies examining physical activity barriers among women, mothers, and caregivers occasionally note feelings of guilt or perceived selfishness when taking time for personal wellness/self-care away from family responsibilities, this is not established in published survey research as a primary or characteristic barrier specific to individuals clinically classified as obese. Established barriers to physical activity in populations with obesity typically center on physical discomfort/pain, weight stigma, body self-consciousness, lack of time, and lack of social support.

Unverified means no publication matching the claim was located; it does not prove the claim false.