Zombie by Day, Owl by Night–Why sleeping preference may be problematic for your waistline.

by Paige on February 19, 2013

Ever wonder where the terms lark and night owl came from?

photo credit: MyAngelG via photopin cc

If you were to ask someone whether or not they would prefer to wake up at 6 AM, it’s likely they will answer with a definitive yes or no. This difference in sleep preference has to do with what scientists call our biological clock. Think about it as what your body wants to do and when it wants to do it.

This is where the night owl and the lark come in: the two classifications of sleepers—the evening people and the morning people. The evening people can stay up until 2-4 AM and then don’t mind sleeping in through the afternoon the following day.  Keep in mind, that night owls exist on a continuum, outside of the 9-5 workday. The morning people are the ones yawning by 9 PM, hitting the sack shortly after, and are rearing to go at the crack of dawn the next day.

For the majority of US adults, the workday starts as early as 7 AM and ends around 5 PM. Only one type of sleeper works really well in this environment, and that’s the morning person. As for the evening people (44% of women and 37% of men, to be exact), this can be problematic. What do you get when you take a night owl and put him into a 9-5 work week?

Sleep deprivation.

photo credit: Magnus. via photopin cc

Researchers are finding that sleep deprivation leads to over-compensating on the weekends–something referred to as “social jetlag”. Which just sets you up for another week of sleeping out of your preferred time schedule, and the cycle perpetuates. Not only this, but a study out of the Journal of Current Biology found that those who were sleeping less during the week, and more on the weekends were more likely to be overweight.

Taken together, research suggests that being a night owl and not getting enough sleep during the week means you have a greater chance of gaining a few extra pounds over the years. Tenuous link?

Don’t reach out for those potato chips just yet…

photo credit: emdot via photopin cc

A study out of the 2013 Journal of Nutrition and Diabetes reported that lack of sleep was significantly associated with an increase in total energy intake in obese subjects. A group of 118 men and women, who had reported sleeping less than 6.5 hours of sleep per night, were followed over 4 years (2007-2011). Sleep patterns and food intake were measured throughout the study period. With just a 30-min deficit in sleep, subjects were predicted to consume 83 calories more per day.

For the night owls who are sleeping less than the recommended 7.5 hours per night during the week, this could suggest some serious calorie packing over the course of the year if not compensated with exercise.

What about exercise, anyway? Lets face it, when you’re tired, the chance of stepping on that treadmill is slim. The thought of pounding your feet against that belt will start to make your head hurt.

photo credit: eccampbell via photopin cc

When researchers looked at a group of non-obese adults during a week of sleep restriction (less than 5.5 hours/night), subjects had 31% lower activity levels and spent 24% less time doing intentional exercise when they were tired. It was estimated that these subjects burned about 250 fewer calories per day when their sleep was restricted.

So, the studies are suggesting that how much sleep you get each night and when you get your sleep don’t just affect how you look at that bag of chips and cardio machine, but both can also strongly influence your productivity and mental alertness (which, has been well established).

As the conflict between our biological clock and society’s social clock continues, it presents an interesting challenge for the night owls to adjust to a routine that goes against their innate preference.  Maybe as industry transitions to a more remote and global work force, we will start to see employees becoming more productive and healthier with flexible hours. Perhaps then we will see less of the “zombie” syndrome that appears to be taking over the cubicle world and costing employers up to $1967/employee every year in productivity losses…sounds to me like a public health solution and a better business model.

photo credit: wvs via photopin cc



 National Sleep Foundation: Waking America to the Importance of Sleep.


Wittmann M. et al. (2006). J. Chron. International. Social Jetlag: Misalignment of Biological and Social Time. doi:10.1080/07420520500545979.

Ronneberg T. et al. (2012). J Current Biology. Social Jetlag and Obesity. doi: 10.1016/j.cub.2012.03.038

Galli G. et al. J Nutr and Diabetes (2013). Inverse relationship of food and alcohol intake to sleep measures in obesity. doi:10.1038/nutd.2012.33.

Penev P.D. (2012). J Clin. Endocrin. & Metab. Update on Energy Homeostasis and Insufficient Sleep. doi:10.1210/jc.2012-1067

Steiropoulos N.E. et al. (2010). J Occup Environ Med. Work Productivity in Obstructive Sleep Apnea Patients. doi: 10.1097/JOM.0b013e3181e12b05.

Rosekind M.R. (2010). J. Occp. & Envir. Medicine. The cost of poor sleep: workplace productivity loss and associated costs. doi: 10.1097/JOM.0b013e3181c78c30