The circadian clock system: one the biggest breakthroughs in metabolism yet
Sleep is one of our body’s ways of conserving energy. Missing out on sleep is linked with metabolic changes that promote fat gain, increased hunger, development of insulin resistance, and altered hormone levels.
Burning the midnight oil skews our body’s delicate biological rhythm, better known as the circadian clock system. The light from the rising morning sun triggers our master hormone center (hypothalamus) to fire the adrenals, elevating cortisol and energizing us for the day. Similarly, evening darkness increases leptin and melatonin, causing us to feel full, satiated, and ready for sleep.
Since light is one of the most important activators of our biological clock system, it’s important that we maximize light exposure in the morning and minimize it at night. Even small amounts of light at night suppress melatonin release and skew our circadian clock, promoting fat gain and making sleep difficult.
Tools That Can Help
Since your brain can’t discern morning sunlight from the short-wavelength (blue) light emitted from the evening use of an electronic reading device, the biological stimulus is the same. Light is stimulating.
Study shows that use of light-emitting e-readers before bed can have a negative impact on sleep
A recent study revealed that the use of light-emitting eReaders (iPads, Nooks, and Kindle Fire) during the four hours leading up to bedtime have dramatically different impacts on sleep and metabolism compared to reading a paperback book in a dimly lit room.
Twelve subjects (six men and six women) spent five days in a sleep center at Brigham and Women’s Hospital in Boston. Evening melatonin levels were measured in the printed book group and the eReader group before the study and after five days of evening use.
The study revealed some shocking results: Subjects using the eReader had reduced melatonin levels, a harder time falling asleep, reduced REM sleep, reduced morning alertness, and biological rhythm imbalances. In contrast, subjects who read a printed book in a dimly lit room didn’t have such sleep, melatonin, biological rhythm, or morning sleepiness imbalances.
– Evening use of light-emitting eReaders skews one’s biological clock.
– Smaller devices may be more distributive because people hold them closer to their faces (iPhones and other mobile devices are likely to cause the same problems).
– If you must stay up late to study or read, try reading an old-fashioned printed book in a dimly lit room.
– Taking 1-3 mg of melatonin in the evening might help offset the damage done by use of eReaders.
– Light exposure at night is deleterious to your health.
-If you must read at night to finish up a project, use blue-light blocking glasses such, as the Uvex
Chang, A.-M., Aeschbach, D., Duffy, J. F., & Czeisler, C. A. (2014). Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proceedings of the National Academy of Sciences, 201418490. doi:10.1073/pnas.1418490112
Link to the study http://www.pnas.org/content/early/2014/12/18/1418490112