If you want to improve your night, begin with your day. As a sleep specialist, I help interpret the countless sleep hacks and tips that pop up in news stories and social feeds. With so much information out there, it is important to filter for information that is both true and helpful. Getting back to the basics of how sleep is regulated helps to simplify, to quiet the noise of  the “improve your sleep with 5 easy tricks” chatter. When it comes to sleep, the role of your circadian rhythm is basic, but recently groundbreaking and surprising as well. 

The word “circadian” translates to “about a day.” Your circadian rhythm is one of the main processes involved in regulating your sleep-wake cycle. Most people have a circadian rhythm that runs a bit longer than the 24-hour light-dark cycle of our planet completing one rotation. In order to keep our master clock in sync, we rely on various inputs into the system. 

You might have already guessed the most powerful input: light. Our eyes contain intrinsically photosensitive retinal ganglion cells. These cells are special because they sense light in a way that is not visual. They communicate information about the quality of the light to the brain to influence how awake and alert we are at a given time. When the sun sets and the light gets dim, the “darkness hormone” of melatonin is produced and secreted from the pineal gland in the brain. We have known for a long time that our bodies have inherent rhythms, but recently the work of three circadian scientists garnered major attention.

In 2017, Jeffrey Hall, Michael Rosbash, and Michael Young were awarded the Nobel Prize in Physiology or Medicine for their work in understanding how our body clocks work on a cellular level. The body clock controls more than sleep, it controls how every cell and system in your body works. When your body clock is out of sync, the complex processes occurring in the body are not optimized as they should be. At different times of day your liver is more efficient, you metabolize food and use glucose differently, the permeability of your blood-brain barrier is altered–these are only a few examples of the wide-reaching impact that proper timing can have on our overall health.

Historically, much attention has been given to duration of sleep. Everyone wants to know how many hours they need to be healthy. While duration has a role, we are now starting to understand how important regularity is in predicting mortality. Results from a study investigating the impact of the consistency of the sleep schedule were published in a January 2024 article in SLEEP, the peer-reviewed journal of the Sleep Research Society. The study found that irregular sleepers were at higher risk for all-cause mortality, as well as death related to both cancer and cardiometabolic disease. The risk associated with not having a regular sleep schedule was calculated to be an even more reliable predictor for poor health outcomes than that of too long or too short sleep. 

Both sleep and your body as a whole function best when a predictable, consistent rhythm is maintained. Start by getting up at the same time every morning, no matter the day of the week. Next, go outside. Remember those special cells in your eyes? Exposure to outdoor light is a strong signal to your circadian rhythm. It will help to keep your master clock in sync and will boost your sleep-wake pattern. When you amplify the curve of your circadian rhythm, you will be more awake and alert during the day resulting in a deeper dive into restful sleep at night. A set wake-up time and morning outdoor light exposure will go a long way toward building the regularity needed to keep you healthy. 

Reference: Daniel P Windred, Angus C Burns, Jacqueline M Lane, Richa Saxena, Martin K Rutter, Sean W Cain, Andrew J K Phillips, Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study, Sleep, Volume 47, Issue 1, January 2024, zsad253, https://doi.org/10.1093/sleep/zsad253