Finding More Time


How to Find More Hours in the Day

Michelle Gumz,Medicine and Biochemistry and Molecular Biology at the University of Florida

Dr. Michelle Gumz is an Assistant Professor of Medicine and Biochemistry and Molecular Biology at the University of Florida. Dr. Gumz received her undergraduate degree in Biochemistry from the University of California Riverside and her Ph.D. from the University of Florida. Dr. Gumz’s post-doctoral training in tumor biology and renal physiology took place at the Mayo Clinic and the University of Florida. The Gumz lab is located in the Division of Nephrology, Hypertension, and Renal Transplantation at the University of Florida where they are working on circadian clock proteins in the regulation of blood pressure and renal function. Dr. Gumz is an active member of APS and currently serves as the Treasurer of the Renal Section and a member of the Women in Physiology Committee.

“Time keeps on slippin’, slippin’, slippin’… into the future1,” sang the Steve Miller band. I grew up listening to this genre of music and these song lyrics often get stuck in my head. Time does indeed seem to slip away more quickly than we would like. These particular song lyrics running through my head is amusing to me because I work on circadian clock proteins, the molecular time keepers of physiological function. It should come as no surprise then that I spend an awful lot of time thinking about time. Although not all readers of this column may consider time as a critical experimental variable, certainly most of us wish we had more time: more hours in the day, more days in the week, etc. I often joke that perhaps I should change the lab’s focus from the kidney clock to the development of a time-turner, like the one Hermione used in Harry Potter and the Prisoner of Azkaban2 to squeeze as much into her schedule as possible. In the absence of magical abilities, what can we do to find more time in the day? One answer to this problem lies in harnessing the power of your body’s circadian clock.

What is your body clock and what does it do? Within nearly every cell of the body is a molecular clock mechanism: a set of core circadian clock proteins mediate oscillations in gene expression, ultimately resulting in daily rhythms in physiological function. This mechanism is strongly conserved across several kingdoms of life and provides an important selective advantage allowing organisms to adapt to their environment3. Blood pressure exhibits a circadian rhythm, as does body temperature, gastrointestinal and immune function, and a number of other physiological processes4. The central clock in the brain is directly entrained by light and food cues contribute to synchronized rhythms among the central clock and peripheral clocks in other tissues. (For excellent reviews on the details see5,6 ). Coordinating the timing of food and light cues and sleep/wake habits can help you and your clock function as efficiently as possible. Time management tips and tricks abound on the internet, but this article will summarize the three best practices that have benefitted my colleagues and me since we began studying circadian biology.

  1. Sleep more! The latest guidelines from the National Sleep Foundation7 suggest that most adults need between 7 – 9 hours sleep every night. Although we might tend to think we can get more done if we sacrifice sleep, getting adequate sleep actually helps us to be more alert, efficient and productive during the day. Studies show that a significant number of adults are chronically sleep deprived with consequences for cardiovascular health8. The consequences of too little sleep are similar to those for other risk factors - increased incidence of cardiovascular disease, obesity, diabetes, and cancer9. A recent meta-analysis demonstrated a U-shaped curve for the relationship between sleep duration and all-cause mortality10, providing a strong argument for getting ~7 hours sleep per night!
  2. Avoid social jet lag! Social jet lag was first defined by Dr. Till Roenneberg of the University of Munich to refer to the misalignment of our internal clocks with our external environment11. To take advantage of your body clock, it helps to know your chronotype. Webster12 defines chronotype as “the internal circadian rhythm or body clock of an individual that influences the cycle of sleep and activity in a 24-hour period.” Most of us can be categorized as “morning larks” or “night owls.” One example of social jet lag would be a night owl forced to be at work by 6 am and thus s/he has to endure a “morning lark” schedule that is misaligned with his/her internal body clock. Social jet lag has been linked to adverse health outcomes and has been documented to occur in several populations and as early as adolescence13,14 . Social jet lag can also stem from keeping one schedule on work days and another on rest days. For many people, this may explain why we feel terrible on Monday mornings. The effect of staying up 3 hours later than your usual bedtime on Friday and Saturday nights effectively shifts your circadian rhythm as if you had traveled back and forth between Miami and Los Angeles for the weekend. Keeping the same sleep schedule on weekends and work days will help you avoid a case of “the Mondays” and could improve your mood and work performance during the week. An acquaintance of mine recently started following this advice and she described the results as “life-changing.” Consistent timing of food intake is also important for synchronizing your body clock3. Staying on the same meal schedule from work days to rest days can potentially be beneficial as well.
  3. Manage your light exposure! The detrimental effects of artificial light at night (ALAN) are well established15. A recent publication in the International Journal of Obesity provided the first population level findings linking ALAN to the obesity pandemic16. A new industry has developed in response to studies like these. Special lighting for the home is available and there are now blue light filter apps for smartphones. Main stream news reports offer suggestions related to reducing our exposure to light at night, including putting phones and computers away well before bedtime17. The blue light emitted by electronic devices travels from the retina to the brain and exposure at night can disrupt circadian function, making your body clock think it’s earlier in the day rather than time for bed. In addition to reducing exposure to ALAN, increasing exposure to natural sunlight during the day is also important! Sunlight is an important entraining cue for the circadian clock. A recent study demonstrated that office workers without a window experienced reduced sleep quality and less sleep time compared to workers with an office window18. A short light break to walk outside and experience sunlight may actually help you sleep better at night, making you feel more rested and allowing you to be more productive.

In summary, to find more time and be more productive during your day, try these three ideas: optimize your light exposure (more natural light earlier in the day and less artificial light from phones/computers late in the day); keep the same sleep/wake and meal schedules on rest and work days; get more sleep!


  1. Steve Miller band, from “Fly like an eagle.” 1976.
  2. Rowling JK. Harry Potter and the Prisoner of Azkaban Scholastic 1999
  3. Dibner C, Schibler U. Circadian timing of metabolism in animal models and humans. J Intern Med. 2015 May;277(5):513-27.
  4. Richards J, Gumz ML. Mechanism of the circadian clock in physiology. Am J Physiol Regul Integr Comp Physiol. 2013 Jun 15;304(12):R1053-64.
  5. Partch CL, Green CB, Takahashi JS. Molecular architecture of the mammalian circadian clock. Trends Cell Biol. 2014 Feb;24(2):90-9
  6. Husse J, Eichele G, Oster H. Synchronization of the mammalian circadian timing system: Light can control peripheral clocks independently of the SCN clock: alternate routes of entrainment optimize the alignment of the body's circadian clock network with external time. Bioessays. 2015 Oct;37(10):1119-28.
  8. Jackson CL, Redline S, Emmons KM. Sleep as a potential fundamental contributor to disparities in cardiovascular health. Annu Rev Public Health. 2015 Mar 18;36:417-40.
  9. Luyster FS, Strollo PJ Jr, Zee PC, Walsh JK; Boards of Directors of the American Academy of Sleep Medicine and the Sleep Research Society. Sleep: a health imperative. Sleep. 2012 Jun 1;35(6):727-34.
  10. Shen X, Wu Y, Zhang D. Nighttime sleep duration, 24-hour sleep duration and risk of all-cause mortality among adults: a meta-analysis of prospective cohort studies. Sci Rep. 2016 Feb 22;6:21480.
  11. Wittmann M, Dinich J, Merrow M, Roenneberg T. Social jetlag: misalignment of biological and social time. Chronobiol Int. 2006;23(1-2):497-509.
  13. Rutters F, Lemmens SG, Adam TC, Bremmer MA, Elders PJ, Nijpels G, Dekker JM. Is social jetlag associated with an adverse endocrine, behavioral, and cardiovascular risk profile? J Biol Rhythms. 2014 Oct;29(5):377-83.
  14. Malone SK, Zemel B, Compher C, Souders M, Chittams J, Thompson AL, Lipman TH. Characteristics Associated With Sleep Duration, Chronotype, and Social Jet Lag in Adolescents. J Sch Nurs. 2016 Apr;32(2):120-31.
  15. Cho Y, Ryu SH, Lee BR, Kim KH, Lee E, Choi J. Effects of artificial light at night on human health: A literature review of observational and experimental studies applied to exposure assessment. Chronobiol Int. 2015;32(9):1294-310.
  16. Rybnikova NA, Haim A, Portnov BA. Does artificial light-at-night exposure contribute to the worldwide obesity pandemic? Int J Obes (Lond). 2016 Jan 22.
  17. Last accessed March 10, 2016
  18. Boubekri M, Cheung IN, Reid KJ, Wang CH, Zee PC. Impact of Windows and Daylight Exposure on Overall Health and Sleep Quality of Office Workers: A Case-Control Pilot Study. J Clin Sleep Med. 2014 Jun 15;10(6):603-11.


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Thank you Dr. Gumz for this incredibly informative article. I was hoping for some great time management tips, but the information you provided is actually more useful. I always tell my children that sleep is as important as nutrition in helping them to be healthy and they have excellent sleep habits. Perhaps I should practice what I preach! I am also fortunate to be moving to an office with a window in the next few months-I will keep you posted on how that affects my sleep.

In addition to the personal applications, the review articles will be especially helpful for me in my A&P lectures. Sleep and circadian rhythms are not covered very well in our textbook. Your supplemental information will be very valuable to my students-both personally and professionally.

Karen M. Mathis, Ph.D.
Assistant Professor
University of Cincinnati


How long does it take someone to change their chronotype? If a night owl were to switch to an early bird schedule, over what period of time would it take for someone to fully adjust?

Karen L. Edelblum, Ph.D.
Assistant Professor and Chancellor Scholar
Department of Pathology & Laboratory Medicine, Center for Inflammation and Immunity
Rutgers New Jersey Medical School


That is a great question! Chronotypes are mostly genetically determined so it may be difficult to make the switch. Any attempt to change over should be done gradually. It may be easier to amend your daily schedule to match your chronotype, but if that is not possible, the concept of keeping the same schedule on rest and work days definitely applies. Night owls who work early morning shifts may place themselves at risk by staying up late and sleeping in on their days off, which would keep them in a constant state of social jet lag. A recent commentary on this subject can be found at:

Michelle L. Gumz, Ph.D.
Assistant Professor
University of Florida

Thank you Michelle for an enlightening Mentoring Forum column! I have a pretty consistent routine for sleep during the week, but I have the classic later bed time and later awake time on the weekends, and I usually get about 1-2 hours extra sleep. How important is the duration of sleep vs. the timing of sleep? Also, do you know of any evidence indicating that diet changes with disordered sleep structure, specifically, your craving for certain foods?

Caroline A. Rickards, Ph.D.
University of North Texas Health Science Center


Very interesting questions! Vitale et al. published a study recently on this very topic (! Evening chronotypes could make up for their work-week sleep debt by sleeping longer on the weekend. For the nutrition question, I found a very recent report from Mota et al. ( suggesting that poor nutrition was associated with an evening chronotype in medical residents. To me, this suggests that your sleep structure may very well be related to food cravings! One of my favorite sources for circadian clock and nutrition news is Bill Lagakos (@caloriesproper on Twitter), he has a great blog at

Michelle L. Gumz, Ph.D.
Assistant Professor
University of Florida