Night Owls May Have Increased Risk of Obesity, Diabetes and Heart Disease Interview with:

Steven K. Malin, PhD, FACSM (he/him) Associate Professor  Department of Kinesiology and Health | School of Arts and Sciences  Division of Endocrinology, Metabolism and Nutrition | Robert Wood Johnson Medical School Institute of Translational Medicine and Science  New Brunswick, NJ 08901

Dr. Malin

Steven K. Malin, PhD, FACSM (he/him)
Associate Professor
Department of Kinesiology and Health | School of Arts and Sciences
Division of Endocrinology, Metabolism and Nutrition | Robert Wood Johnson Medical School
Institute of Translational Medicine and Science
New Brunswick, NJ 08901 What is the background for this study?

Response: Type 2 diabetes is a condition where blood glucose (sugar) is elevated in the  blood. This can be problematic as it leads to blood vessel damage and the promotion of cardiovascular disease. Nearly 30 million people  in the U.S. have type 2 diabetes, making it a major public health issue. The cause is not entirely clear, but many, including our team view insulin resistance as a central culprit.

Insulin resistance is when the body does not respond well to the hormone insulin. Insulin is vital because it promotes glucose uptake into tissues, like skeletal muscle. Two reasons that are often used to explain the development of insulin resistance include: poor diet (e.g. high sugar and/or high fat coupled with excess calories) and a lack of physical activity. However, more recently, a lack of sleep has been raised as another critical behavioral factor contributing to insulin resistance. Thus, targeting a healthy diet, activity and sleep pattern is thought to prevent the transition from health to insulin resistance and type 2 diabetes. What are the main findings?

Response:  In line with above, sleep is considered important for lowering type 2 diabetes risk. However, sleep itself is just one factor. Embedded within sleep is the idea we sleep get enough and good quality. Something that impacts our ability to sleep is the notion of chronotype.

Chronotype (e.g. early bird vs. night owl) is the preference a person has towards performing acts of daily living. People of late chronotype or “night owls” are reported to have higher risk of obesity, type 2 diabetes and cardiovascular disease when compared with earlier chronotypes. A potential explanation is they become misaligned with their circadian rhythm for various reasons, but most notably among adults would be work. For instance, if one is a late owl they prefer going to bed later. However, they must still wake up to do a variety of things (e.g. take care of kids, get to work, etc.) that may “force” them to be out of alignment with when people would rather be sleeping still. This changes their physiology and increases disease risk. We wondered in this study if the change in physiology relates to insulin resistance through changes in their fat metabolism. No prior work to our knowledge measured insulin resistance using “gold-standard” approaches of the euglycemic clamp along with indirect calorimetry to determine fat metabolism. Further, no work to our knowledge characterized metabolism during exercise. Measuring metabolism during rest and exercise allowed us to see how changes in movement throughout the day could impact or relate to health. A key finding was that individuals with later chronotype were indeed less able to respond to insulin by promoting glucose uptake towards storage. And that observation related to how much fat was used for energy. This aligns with ideas that low fat metabolism relates to insulin resistance by either defects in the mitochondria (i.e. powerhouse of the cell that makes energy) or accumulation of fat metabolites that impair insulin action on tissues like muscle. What should readers take away from your report?

Response: My general advice is: get moving! Moving throughout the day is a great way to foster health. This doesn’t have to be intense movement either. Rather breaking up sedentary behavior for about 2 minutes every hour during the day, or taking 10-15 min brisk walks after meals can go a long way. On top of that doing a variety of movements (body weight lifts – body squats, push-ups, sit and stands, etc.). This will help engage different parts of the body to improve health. Doing these activities earlier in the day too may offer some help towards weight management and help the body prepare for bed.

As a result, avoiding stressful or vigorous activity late in the evening can help prepare the body for sleep. Getting into a routine for healthy sleep would also include minimizing stimulating foods (e.g. high sugar, caffeine, etc) along with cutting out technology (e.g. phones, IPADs, etc.) with blue lights. This later point is important as it can “trick” our circadian clocks into staying awake. Leaving such devices out of the bedroom can really help and use that time before bed to read and relax.

Lastly, people who are late chronotypes that wish to try and align their body with work schedules and so forth can take small steps towards shifting to be an early bird. One approach is use 15 minute windows to adjust. So go to bed 15 minutes earlier then wake up 15 minutes earlier. In time and depending on how things are going, this can expand another 15 minute window. Then during the earlier time waking up, a person can engage in light physical activity to help with promoting general fitness. In they can get outside with sunlight, that would be great too as the natural sun light would provide cues to the circadian system to adjust. What recommendations do you have for future research as a results of this study?

Response: My general recommendation would be to consider different populations. We focused on middle-aged to older adults with obesity/metabolic syndrome. Whether this occurs in kids/young adults or even middle-aged to older adults without obesity or cardiometabolic disease is worth considering. Further, I think we need to consider more mechanistic studies to show at the cell levels how some of the differences in metabolism may occur. Is there anything else you would like to add? Any disclosures?

Response: I think these findings fit with current public health discussions. Notably, the US government is discussing making day light savings permanent. While understanding the rationale, most research suggests standard time is better from a circadian rhythm perspective. In fact, standard time is linked to lower heart disease as well as accidents and performance in work. A reason I wonder for these observations may be the natural alignment of how our body aligns with natural sunlight and nighttime. If we promote a timing pattern that is how of sync with nature, it could exacerbate health risk on levels. Other examples of this fit with discussions on when school should start for children to better align with their need for sleep and cognitive ability. Moreover, this fits with ideas of night-shift work and the challenges these jobs place on risk of disease. Depending on work schedules overall, some may have requirements that ultimately contribute to disease risk. Whether dietary patterns or activity can help attenuate these is  an area we hope becomes clearer in time for well-being of all.


Malin, S. K., Remchak, M.-M. E., Smith, A. J., Ragland, T. J., Heiston, E. M., & Cheema, U. (2022). Early chronotype with metabolic syndrome favours resting and exercise fat oxidation in relation to insulin-stimulated non-oxidative glucose disposal. Experimental Physiology, 00, 1-10.

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Last Updated on September 26, 2022 by Marie Benz MD FAAD