Dr Dean J Miller
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drdeanjmiller.bsky.social
Dr Dean J Miller
@drdeanjmiller.bsky.social
Sleep Scientist | Senior Lecturer
Have a gander at my new piece in the Conversation!
June 25, 2025 at 11:00 PM
Have you ever been told to “go and touch some grass”?

In this piece, myself and Charlotte Gupta (notoriously grounded individuals 👀 ) discuss the science behind grounding.

Link below 👇
Social media is awash with content promoting grounding mats and sheets. Could they really help you sleep better?
What is grounding and could it improve my sleep? Here’s the science behind this TikTok trend
theconversation.com
May 14, 2025 at 5:53 AM
‼️NEW RESEARCH‼️

Excited to share our latest paper led by Dr. Matthew Morrison!

journals.humankinetics.com/view/journal...
February 23, 2025 at 11:13 PM
If you were going to run 100 miles (161 km), would you stop to sleep? Or push through?

Find out the most common approaches to sleep during ultra-marathons, and our thoughts on future strategies in our open access paper.

mdpi.com/1720578

@academic-chatter.bsky.social @phdvoice.bsky.social
December 5, 2024 at 2:06 AM
🚨If you (1) sleep; and (2) wear a device that measures sleep/heart rate/ heart rate variability. Here is a thread explaining (briefly) our recent validation of 6 commonly used wearables🧵

doi.org/10.3390/s221...
A Validation of Six Wearable Devices for Estimating Sleep, Heart Rate and Heart Rate Variability in Healthy Adults
The primary aim of this study was to examine the validity of six commonly used wearable devices, i.e., Apple Watch S6, Garmin Forerunner 245 Music, Polar Vantage V, Oura Ring Generation 2, WHOOP 3.0 a...
doi.org
November 29, 2024 at 8:02 AM
Such a great chat with my childhood mate, former teammate, and now Emergency Physician Dr Akash Patel.

shorturl.at/RHOMB
November 27, 2024 at 6:51 AM
🚨 NEW PAPER 🚨

Have you ever noticed how alcohol impacts your sleep?

Our new paper, led by Dr Carissa Gardiner is now available as an online pre proof.

#sleep #sleepscience #alcohol

www.sciencedirect.com/science/arti...
The effect of alcohol on subsequent sleep in healthy adults: A systematic review and meta-analysis
Alcohol is commonly consumed prior to bedtime with the belief that it facilitates sleep. This systematic review and meta-analysis investigated the imp…
www.sciencedirect.com
November 21, 2024 at 10:32 AM
G’day, I’m a sleep scientist from Australia. If you like to sleep, then follow me. 🤣 #scientist #sleep
November 21, 2024 at 9:12 AM
If you were going to run 100 miles (161 km), would you stop to sleep? Or push through?

Find out the most common approaches to sleep during ultra-marathons, and our thoughts on future strategies in our new open access paper.

@darren__bianchi @sleeppsyc

mdpi.com/1720578
Running on Empty: Self-Reported Sleep/Wake Behaviour during Ultra-Marathon Events Exceeding 100 Miles
The aim of this study was to examine sleep/wake behaviour and sleep strategies before, during and after ultra-marathon running events exceeding 100 miles (161 km). A total of 119 athletes completed a web-based questionnaire regarding their habitual sleep/wake behaviour before, during, and after ultra-marathon participation. Event-specific data were grouped by race distance categories; 100–149 miles (161–240 km), 150–199 miles (241–321 km), and ≥200 miles (322 km). Athletes commonly reported not sleeping throughout the duration of their races (74%). However, for events that were ≥200 miles, athletes reported more sleep opportunities, longer sleep duration, and more total sleep when compared to events that were 100–149 miles in distance (p ≤ 0.001). This suggests that for races of shorter distances, the benefit of continuous racing outweighs the negative impact of continuous wakefulness/sleep deprivation. However, for longer races (≥200 miles), there is an apparent tradeoff between sleep deprivation and race strategy, whereby athletes cannot sustain a desired level of performance without obtaining sleep. This is consistent with established sleep/wake behaviour models suggesting that sleep need increases as wakefulness increases, or in this case, as race duration increases. For athletes participating in ultra-marathons, sleep management education and/or consultation with a sleep scientist prior to racing may be beneficial. Future research should examine the optimal strategies concerning the frequency and duration of sleep during ultra-marathons and the subsequent impact on performance.
mdpi.com
January 30, 2025 at 9:25 PM
It was great to be a part of the @Sleep4Perform Seminar yesterday presenting our work regarding sleep during ultra-marathons. A lot of work to be done in this area 👀

x.com/msprajcer/stat… doi.org/10.3390/ijerph…
Sleep–Wake Behaviour of 200-Mile Ultra-Marathon Competitors: A Case Study
The aim of this study was to examine the sleep–wake behaviour of 200-mile ultra-marathon runners before, during, and after a competition. A longitudinal, observational study was conducted to collect the sleep data of four (two females; mean age: 45.5 ± 3.1 years) runners competing in a 200-mile ultra-marathon (N = 4). Wrist-worn activity monitors, in conjunction with self-report sleep diaries, were used to measure sleep, beginning seven days prior to the race and concluding seven days following the race (2–19 June 2021). Descriptive analysis of runners’ subjective and objective sleep data was conducted. All runners completed the 200-mile event in an average of 82.5 ± 7.1 h. On average, runners obtained 4.7 ± 3.0 h of sleep from 4.8 ± 2.4 sleep episodes, averaging 59.9 ± 49.2 min of sleep per episode. Runners averaged 6.0 ± 1.3 h of sleep per night in the week before the competition and 6.3 ± 1.3 h per night in the week following the competition. Runners in the 200-mile (326 km) ultra-marathon drastically restricted their sleep. However, obtained sleep, the number of sleep episodes, and sleep episode length were greater than those previously reported with 100-mile (161 km) runners. In-race sleep data suggest an increased need for sleep as race duration increases. Interestingly, runners obtained less than the recommended ~8 h of sleep per night, in both pre-race and post-race phases of the competition.
doi.org
January 30, 2025 at 9:25 PM
“It’s not just what you eat, but when”.

Chrononutrition Masterclass from @cc_gupta today at the @Sleep4Perform conference. Also heard from FMRS guru @msprajcer, with @ashmontero_ & @SSHRoberts to come in the evening session. Tune in if you can! #sleepscience
January 30, 2025 at 9:25 PM
Trying to find new ways to share our research on social media. If interested, take a look at the quick snapshot of our latest paper on my Instagram. If you love it, let me know, if you hate it, let me know (nicely) 😅

instagram.com/reel/CayZWnMA4… mdpi.com/1660-4601/19/5…
Sleep–Wake Behaviour of 200-Mile Ultra-Marathon Competitors: A Case Study
The aim of this study was to examine the sleep–wake behaviour of 200-mile ultra-marathon runners before, during, and after a competition. A longitudinal, observational study was conducted to collect the sleep data of four (two females; mean age: 45.5 ± 3.1 years) runners competing in a 200-mile ultra-marathon (N = 4). Wrist-worn activity monitors, in conjunction with self-report sleep diaries, were used to measure sleep, beginning seven days prior to the race and concluding seven days following the race (2–19 June 2021). Descriptive analysis of runners’ subjective and objective sleep data was conducted. All runners completed the 200-mile event in an average of 82.5 ± 7.1 h. On average, runners obtained 4.7 ± 3.0 h of sleep from 4.8 ± 2.4 sleep episodes, averaging 59.9 ± 49.2 min of sleep per episode. Runners averaged 6.0 ± 1.3 h of sleep per night in the week before the competition and 6.3 ± 1.3 h per night in the week following the competition. Runners in the 200-mile (326 km) ultra-marathon drastically restricted their sleep. However, obtained sleep, the number of sleep episodes, and sleep episode length were greater than those previously reported with 100-mile (161 km) runners. In-race sleep data suggest an increased need for sleep as race duration increases. Interestingly, runners obtained less than the recommended ~8 h of sleep per night, in both pre-race and post-race phases of the competition.
www.mdpi.com
January 30, 2025 at 9:24 PM
Our latest paper examined the effectiveness of a circadian adaptation schedule in male cricketers after eastward flight (i.e., reducing "jet lag")

Acquiring a daily circadian biomarker with athletes in the field was challenging and enjoyable!

OPEN ACCESS

mdpi.com/2076-3417/11/2…
Implementing a Circadian Adaptation Schedule after Eastward Flight in Young Male Athletes
This study examined the effectiveness of a circadian adaptation schedule in male cricketers after an 8.5 h eastward time zone change. Ten participants (aged 18.7 ± 0.9 y) were randomly assigned to a control group or an intervention group. Participants in the intervention group followed a light exposure schedule in which they were instructed to seek light in the three hours preceding, and avoid light in the three hours following their estimated core body temperature minimum. The rate of adaptation was assessed using the nightly excretion rate of urinary 6-sulphatoxymelatonin (aMT6s). General linear mixed models were conducted to assess the effect of condition (i.e., control and light intervention) on nocturnal secretion of aMT6s. Significant main effects of day (F(7, 35) = 10.4, p < 0.001) were reflected by an increase in nocturnal melatonin excretion (i.e., all participants gradually adapted to the destination time zone). Subjective jet lag decreased by day (F(7, 54) = 22.9, p < 0.001), bedtime was delayed by day (F(7, 54) = 3.1, p = 0.007) and get up time was earlier by day (F(7, 35) = 5.4, p < 0.001). On average, it took 7 days for all participants to return to baseline levels following transmeridian travel. Similarly, it took 7 days for subjective jet lag to alleviate. In the initial 4 days of the protocol, the intervention group registered higher levels of nocturnal urinary melatonin, however, there was no significant differences in the rate of adaptation between the groups. It is possible that participants did not adhere to the intervention or that they followed the intervention but it was ineffective.
www.mdpi.com
January 30, 2025 at 9:24 PM
Nice to see this paper still gaining 👀

We examined the😴 of fit young males in no exercise 🛋️, aerobic exercise 🚴‍♂️, & resistance exercise 🏋️conditions (🛑@ 21:30)

Body temp⬆️after🚴‍♂️but returned to baseline before bedtime. Sleep did not differ across conditions.

FREE ACCESS:

x.com/EurJSportSci/s…
January 30, 2025 at 9:24 PM
Blowing the whistle on inadequate sleep? Have a look at our latest work led by @sleeppsyc 😴

@AcademicChatter

x.com/SciMed_Footbal…
January 30, 2025 at 9:23 PM
I am so proud of my wife, who today started her 3.5 month Dietetics placement on Mparntwe Land (Alice Springs).
January 30, 2025 at 9:23 PM
Over half of the 32 respondents below self reported increases in sleep and exercise during physical distancing. Click the link below to see how >5,000 individuals altered their health related behavior during the pandemic.

New paper in PLOS ONE:

x.com/drdeanjmiller/… doi.org/10.1371/journa…
How has your relationship with exercise and/or sleep altered during the pandemic? (poll below)

Our new paper, in collaboration with @whoop, looks at changes in health promoting behaviour during physical distancing restrictions.

OPEN ACCESS link below:

dx.plos.org/10.1371/journa…
Changes in health promoting behavior during COVID-19 physical distancing: Utilizing wearable technology to examine trends in sleep, activity, and cardiovascular indicators of health
The COVID-19 pandemic incited unprecedented restrictions on the behavior of society. The aims of this study were to quantify changes to sleep/wake behavior and exercise behavior, as well as changes in physiological markers of health during COVID-19 physical distancing. A retrospective analysis of 5,436 US-based subscribers to the WHOOP platform (mean age = 40.25 ± 11.33; 1,536 females, 3,900 males) was conducted covering the period from January 1st, 2020 through May 15th, 2020. This time period was separated into a 68-day baseline period and a 67-day physical distancing period. To provide context and allow for potential confounders (e.g., change of season), data were also extracted from the corresponding time periods in 2019. As compared to baseline, during physical distancing, all subjects fell asleep earlier (-0.15 hours), woke up later (0.29 hours), obtained more sleep (+0.21 hours) and reduced social jet lag (-0.13 hours). Contrasting sleep behavior was seen in 2019, with subjects falling asleep and waking up at a similar time (-0.01 hours; -0.03 hours), obtaining less sleep (-0.14 hours) and maintaining social jet lag (+0.06 hours) in corresponding periods. Individuals exercised more intensely during physical distancing by increasing the time spent in high heart rate zones. In 2020, resting heart rate decreased (-0.90 beats per minute) and heart rate variability increased (+0.98 milliseconds) during physical distancing when compared to baseline. However, similar changes were seen in 2019 for RHR (-0.51 beats per minute) and HRV (+2.97 milliseconds), suggesting the variation may not be related to the introduction of physical distancing mandates. The findings suggest that individuals improved health related behavior (i.e., increased exercise intensity and longer sleep duration) during physical distancing restrictions. While positive changes were seen to cardiovascular indicators of health, it is unclear whether these changes were a direct consequence of behavior change.
dx.plos.org
January 30, 2025 at 9:23 PM
How has your relationship with exercise and/or sleep altered during the pandemic? (poll below)

Our new paper, in collaboration with @whoop, looks at changes in health promoting behaviour during physical distancing restrictions.

OPEN ACCESS link below:

dx.plos.org/10.1371/journa…
Changes in health promoting behavior during COVID-19 physical distancing: Utilizing wearable technology to examine trends in sleep, activity, and cardiovascular indicators of health
The COVID-19 pandemic incited unprecedented restrictions on the behavior of society. The aims of this study were to quantify changes to sleep/wake behavior and exercise behavior, as well as changes in physiological markers of health during COVID-19 physical distancing. A retrospective analysis of 5,436 US-based subscribers to the WHOOP platform (mean age = 40.25 ± 11.33; 1,536 females, 3,900 males) was conducted covering the period from January 1st, 2020 through May 15th, 2020. This time period was separated into a 68-day baseline period and a 67-day physical distancing period. To provide context and allow for potential confounders (e.g., change of season), data were also extracted from the corresponding time periods in 2019. As compared to baseline, during physical distancing, all subjects fell asleep earlier (-0.15 hours), woke up later (0.29 hours), obtained more sleep (+0.21 hours) and reduced social jet lag (-0.13 hours). Contrasting sleep behavior was seen in 2019, with subjects falling asleep and waking up at a similar time (-0.01 hours; -0.03 hours), obtaining less sleep (-0.14 hours) and maintaining social jet lag (+0.06 hours) in corresponding periods. Individuals exercised more intensely during physical distancing by increasing the time spent in high heart rate zones. In 2020, resting heart rate decreased (-0.90 beats per minute) and heart rate variability increased (+0.98 milliseconds) during physical distancing when compared to baseline. However, similar changes were seen in 2019 for RHR (-0.51 beats per minute) and HRV (+2.97 milliseconds), suggesting the variation may not be related to the introduction of physical distancing mandates. The findings suggest that individuals improved health related behavior (i.e., increased exercise intensity and longer sleep duration) during physical distancing restrictions. While positive changes were seen to cardiovascular indicators of health, it is unclear whether these changes were a direct consequence of behavior change.
dx.plos.org
January 30, 2025 at 9:23 PM
For those exiting lockdown today please take care on the roads! Pandemic data has shown delays in sleep timing during physical distancing restrictions - i.e., going to bed and waking up later. Many have likely woken up earlier for work this morning with suboptimal sleep😴
January 30, 2025 at 9:23 PM
To add to this - last night, while asleep, I apparently told my wife to use absolute differences when comparing sleep wearables to polysomnography... 🤦‍♂️ #talkingsleepduringsleep

x.com/drdeanjmiller/…
Data obtained from my wearable device while presenting about the validity of wearable devices #meta

📉Drop in HR is start of question time🙋‍♀️
January 30, 2025 at 9:23 PM
Data obtained from my wearable device while presenting about the validity of wearable devices #meta

📉Drop in HR is start of question time🙋‍♀️
January 30, 2025 at 9:23 PM
Planning a study protocol vs first pilot run 😅
January 30, 2025 at 9:22 PM
Pints, punts and poor sleep? 🍻 💰 😴

Alcohol and gambling problems appear to be linked to insomnia 🥱

+ gambling problems may lead to poorer subjective sleep quality 💤

Read more below ⬇️

Great work from @gamblinghannah et al.

mdpi.com/1660-4601/18/1…
Gambling Problems Are Associated with Alcohol Misuse and Insomnia: Results from a Representative National Telephone Survey
Gambling has significant costs to the community, with a health burden similar in scale to major depression. To reduce its impact, it is necessary to understand factors that may exacerbate harm from gambling. The gambling environment of late-night licensed venues and 24/7 online gambling has the potential to negatively impact sleep and increase alcohol consumption. This study explored gambling, alcohol, and sleep problems to understand whether there is a relationship between these three factors. Telephone interviews were conducted with a representative sample of Australian adults (n = 3760) combined across three waves of the National Social Survey. Participants completed screening measures for at-risk gambling, at-risk alcohol consumption, insomnia (2015 wave only), and sleep quality. There were small but significant positive correlations between problem gambling and alcohol misuse, problem gambling and insomnia, and problem gambling and poor sleep quality. A regression model showed that gambling problems and alcohol misuse were significant independent predictors of insomnia. A separate regression showed gambling problems (and not alcohol misuse) were a significant predictor of poor sleep quality, but only in one survey wave. Findings suggest that gambling, alcohol, and sleep problems are related within persons. Further research should examine the mechanisms through which this relationship exists.
www.mdpi.com
January 30, 2025 at 9:22 PM
More outstanding work from @cc_gupta and team:

The Relationship Between Diet and Sleep in Older Adults: a Narrative Review 🍒🥛@AcademicChatter #SleepPeeps

x.com/cc_gupta/statu… link.springer.com/article/10.100…
The Relationship Between Diet and Sleep in Older Adults: a Narrative Review
Current Nutrition Reports - Older adults more frequently experience reduced sleep quality and quantity compared to younger adults. Diet is one modifiable lifestyle factor that may influence sleep...
link.springer.com
January 30, 2025 at 9:22 PM