HSN – New research on dusk/dawn light, exercise, and collagen

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Health Scoop News 📑 – New research on dusk/dawn light, exercise, and collagen

I always have my nose in new health research, so I’m sharing some of the most relevant studies with you in regular editions of “Health Scoop News.”

[This news summary is a bit reminiscent of my old “This week in science for holistic health” newsletters that I used to do circa 2016 (I deleted most, but here’s one post I kept live), as well as the rEATsearch podcast I used to co-host.]

How do researchers decide which studies to include in their reviews of several studies?

If you’re curious as to how researchers choose which studies to include in their reviews (why do some include 10 and others 190)? the criteria to include a study in a review has to be decided before any searching is done.

And this is definitely done before the results or conclusions are known.

This inclusion criteria should be clearly stated in the “methods” part of the review so that you or I or anyone reading the study can search the same databases to recreate the same results.

This is to reduce bias and get a more accurate overview of a topic.

A scientific review would:

  1. Define the question they want to answer.
  2. Define the type of studies that can help formulate a non-biased answer (e.g., What type of study is needed? What should the study have measured? What databases are these studies in? What keywords will help to find them all?).
  3. Only then do they run their searches, look at each study’s methods (not conclusions), and include all studies that meet this criteria, regardless of what the studies concluded.

This is why it’s important to put more emphasis on higher quality studies (e.g. randomized control trials and meta analyses) and less emphasis on lab studies done on cells or animals. And that’s why I only include high-quality studies in this newsletter.

These are my top three study picks (comment below to tell me what health topics/niches are best for you!). All are very high quality studies (most are studies that review and analyze data from several previous studies, not just one or two).

These studies were all published in the past month or so.

1 – Reduce bright, blue light from dusk to dawn for better sleep (and a more balanced circadian cycle)

Study title: The importance of residential dusk and dawn light exposure for sleep quality, health, and well-being

This is a review of 23 clinical studies that looked at the effects of dawn and/or dusk simulation, typically applied at a home (like) environment.

Here’s some background info:

  • Light that enters the human eye enables vision and perception. Additionally, it triggers signals to various brain regions with a specific focus on the human biological clock.
  • During evolution, human rest/activity cycles have synchronised with light and dark diurnal patterns. Therefore, light is seen as the most important ‘zeitgeber’ for the human biological clock that, amongst other functions, orchestrates sleep.
  • Since the effects of home lighting during twilight periods on sleep and well-being have yet received relatively little scientific attention, the current paper aims to discuss the importance of twilight (dusk/dawn) simulation (at home) for sleep and subsequent health and well-being as well as the evidence and potential of twilight simulation (at home) to facilitate better sleep and well-being.
  • Twilight is not the only time of day that light can influence (circadian) functioning and well-being. Everyday light exposure matters at any time, and light exposure beyond twilight influences sleep and well-being.

Here’s what the researchers concluded:

  • People’s lack of exposure to natural or electric light (with equivalent characteristics) at home during dusk and dawn can have significant detrimental effects on sleep and well-being.
  • Studies in this review pointed to a clear potential of dawn simulation to improve sleep and daytime well-being and functioning.

In other words, according to this study, the colour and brightness of light entering the eye are the most important factors for better circadian cycles and sleep. At dusk, try to simulate dusk even when indoors (lower the brightness and move away from blue/white light to light that is similar to that of a sunset). Keep light “dusk-like” until sleep and turn lights off when going to sleep. At dawn and throughout the day, simulate “dawn-like” brighter light (with more blue/white light) to help stay awake and alert.

For more information, here is a link to the study: https://www.sciencedirect.com/science/article/pii/S1087079223001211?via%3Dihub

2 – Exercise for better cognition

Study title: Physical activity on executive function in sedentary individuals: Systematic review and meta-analysis of randomized controlled trials

This study reviewed clinical trials that included sedentary people randomized into a physical activity group or no physical activity group and looked at their executive function. After searching several databases of studies to find ones that meet this criteria, a total of 13 studies were included and reviewed in this meta-analysis.

Here’s some background info:

  • Executive function (EF) is a top-down, higher-order cognitive functions that are responsible for reasoning, planning, regulating, controlling information processes and behaviors. This includes:
    • Inhibitory control (the capacity to suppress strong or inappropriate impulses from within or from the outside)
    • Working memory (the ability to store information in the mind for short periods of time and is essential for reasoning and problem solving)
    • Cognitive flexibility (the ability to adjust flexibly to changing needs or priorities)
  • Sedentary behavior (sitting, lying down) is associated with poorer executive function. High levels of sedentary behavior are linked to an increased risk of chronic conditions, such as obesity, type 2 diabetes, cardiovascular disease, and mental illness.
  • Physical activity (any movement of the body that elevates energy expenditure beyond that at rest) is good for physical health and produces positive effects on executive function.

Here’s what the researchers conclude:

  • Physical activity is a potentially effective strategy for improving executive function in sedentary individuals, with improvements in inhibitory control and working memory.
    • Results showed a small to moderate beneficial effect of physical activity on executive function.
    • Interventions with an intervention length >12 weeks improved overall executive function, but intervention length ≤12 weeks did not.
    • Interventions with session time ≥45 minutes improved overall executive function, but session time <45 minutes did not.
    • Physical activity improves executive function for older adults (age ≥60 years), but not for younger individuals (age <60 years).

In other words, this study found measurable improvements in executive function (inhibitory control and working memory) when sedentary people over the age of 60 exercised for at least 45 minutes, 1-4 times per week, for at least 12 weeks.

For more information, here is a link to the study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10703253/


For a list of dozens of credible sites to find health information, plus some PubMed tips, download your free guide here:


3 – Yes, collagen helps the skin

Study title: Exploring the Impact of Hydrolyzed Collagen Oral Supplementation on Skin Rejuvenation: A Systematic Review and Meta-Analysis

Leesa’s Disclosure: I take collagen almost every day. I learned about its skin benefits years ago when researching a client article about hyaluronic acid. Plus, I don’t eat a lot of meat or poultry and can use a bit more protein in my diet, so out of all of the protein supps, I chose collagen. (And I also use SPF daily for my skin).

This is a review of 14 clinical trials that tested the impact of oral hydrolyzed collagen supplements on the skin. Yes, it appears that collagen might in fact be an effective anti-aging supplement for the skin.

Here’s some background info:

  • Collagen is a vital structural protein found in diverse connective tissues like skin, tendons, cartilage, and bone, making up a substantial fraction, roughly 25-30%, of the total proteins in the human body.
  • Hydrolyzed collagen is rich in amino acids such as hydroxyproline, proline, and glycine, which are absorbed as dipeptides and transported to the skin. These dipeptides enhance the bioactivity of dermal fibroblasts by stimulating collagen synthesis, thereby improving skin moisture levels and elasticity.
  • Based on the research reviewed, no one reported any side effects from consuming collagen. Hydrolyzed collagen supplements are commonly derived from bovine, marine animals, and chicken. This means that if the consumers are allergic to beef, fish, or poultry, they could have a reaction after consuming collagen supplements.
  • This study aims to know the powerful effect of hydrolyzed collagen on the skin. This research method is to conduct a systematic review followed by a meta-analysis of the clinical trial focusing on randomized, double-blind, and controlled trials that examined the oral consumption of hydrolyzed collagen and reported outcomes related to skin aging, wrinkles, moisture levels, elasticity, and firmness.

Here’s what the researchers conclude:

  • It consistently demonstrated substantial enhancements in skin moisture levels and elasticity compared to the placebo group, a trend robustly corroborated by subgroup analysis.
  • These compelling findings underscore the effectiveness of a 12-week regimen of hydrolyzed collagen supplementation in revitalizing the skin by augmenting its hydration and elasticity.
  • The mechanism by which hydrolyzed collagen improves skin elasticity and hydration involves the stimulation of collagen synthesis, an increase in moisture content within the stratum corneum, and the reinforcement of the skin’s natural barrier. These combined effects contribute to overall skin health and vitality, making collagen supplements effective in preserving rejuvenation and maintaining a well-nourished complexion.
  • Research shows a safe and effective dose for skin rejuvenation is 300 mg to 5 grams of hydrolyzed collagen peptides daily.
  • Hydrolyzed collagen will provide benefits if consumed for more than four weeks.

In other words, taking 0.3-5 grams of hydrolyzed collagen supplement (powder or capsule) every day for at least four weeks can measurably improve the skin’s hydration and elasticity. It is not ideal for strict vegetarians or vegans, though because it is animal-based.

For more information, here is a link to the study: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10773595/

Signing off and toasting: To keeping up with the latest and greatest scientific research in nutrition, fitness, and health coaching!


Over to you


Do you have a specific question about any of these new studies?

Are you looking for a easy-to-understand study summary that you can share with your audience and clients?

What health topic/niche is most important to you?

Let me know in the comments below!


What's the latest health research for your nutrition, fitness, or health coaching practice?

Find out in the weekly Health Scoop News 📑email updates. See some of the latest studies (with Leesa's "in other words" explainers) here. Sign up if you want to be first to know new research:

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I'm Leesa Klich, MSc., R.H.N.
Health writer – Blogging expert – Research nerd.

I help health and wellness professionals build their authority with scientific health content. They want to stand out in the crowded, often unqualified, market of entrepreneurs. I help them establish trust with their audiences, add credibility to their services, and save them a ton of time so they don’t have to do the research or writing themselves. To work with me, click here.


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