Can The Circadian Rhythm Be Changed?

Human beings are equipped with an elegant internal clock that keeps our bodies working like well-oiled machines. But from time to time, those machines may be subject to a little wonkiness. And while circadian rhythm disruptions are pretty common among shift workers, emergency room doctors, and pilots, these shifts can affect any of us at any given time. But there’s no reason to lose sleep over losing sleep. You may not be able to reset your circadian rhythm per se, but you can shift it earlier or later and get things back on track — it can’t be done overnight (no pun intended), but it can be done.

Note: The content on Sleepopolis is meant to be informative in nature, but it shouldn’t be taken as medical advice, and it shouldn’t take the place of medical advice and supervision from a trained professional. If you feel you may be suffering from any sleep disorder or medical condition, please see your healthcare provider immediately.

Long Story Short

Circadian rhythms are roughly 24-hour internal cycles that help regulate various processes, such as sleep and digestion.
Circadian rhythms are sensitive to disruption and inconsistency
You can shift your circadian rhythm earlier or later by shifting your bedtime, exercising earlier in the day, and managing your exposure to light.

What Is A Circadian Rhythm?

Stephanie Griggs, Ph.D., RN, FAAN, and Assistant Professor at Frances Payne Bolton School of Nursing, tells Sleepopolis that “Circadian is derived from the Latin phrase ‘circa diem,’ which translates to ‘about a day.’ It is a 24-hour natural internal process to regulate the sleep-wake cycle.”

More specifically, your circadian rhythm is your body’s internal clock that regulates your temperature, eating habits, and digestion over a 24-hour time period. But as Griggs points out, one of the most important functions of your brain’s master clock is responding to light and dark cues to regulate your sleep and wake cycles. Bright light (like sunlight) makes us feel more alert and awake, while low light (think sunset) makes us feel sleepy.

In addition to natural stimuli, the circadian rhythm is guided by influences such as artificial light, meal times, bedtime routines, and stress levels. Though the internal clock is designed to respond to environmental cues, we can exert some control over it if need be.

Can You Reset Your Circadian Rhythm?

According to Dr. Jay Olson, a Postdoctoral Scholar at McGill University who studies sleep and circadian rhythms, “Circadian rhythms cannot be ‘reset’ per se, but it is possible to shift your circadian rhythm so that you fall asleep earlier or later.”

Essentially, our circadian rhythms are not like an iPhone; you can’t restore it to its factory settings and start over. Circadian rhythms will respond to change, but those changes must be gradual.

“Circadian rhythms should be shifted slowly, usually by around half an hour to an hour per day.”
Dr. Jay Olson, Postdoctoral Scholar

Factors that May Disrupt Your Circadian Rhythm

While most people will find that disruptions to their circadian rhythms come courtesy of things like sleeping in later on the weekends and crossing time zones while traveling, there are a few other factors that can disrupt your circadian rhythm.

Light

With more people spending more time indoors under artificial lights, circadian rhythms are likely to see an uptick in irregularities. This is especially true for those who are exposed to bright artificial lights later in the day — the net effect is that their circadian rhythms are pushed later. As a result, these folks will likely find it more difficult to fall asleep and even more difficult to wake up the next morning.

“Light is the primary time synchronizer, and that includes blue light from a screen (phone or TV),” says Griggs. “Watching TV late at night or having a TV in the bedroom along with looking at a smartphone close to bedtime sends a message to your brain to stop secreting melatonin.” And when that happens, you can bet the blow to your circadian rhythm will follow.

Moreover, blue light can boost mood and alertness and improve cognition, so exposure to blue light is crucial during our waking hours. However, the blue light emitted from our favorite devices in the evening hours can be problematic as it meddles with our melatonin production and disrupts our circadian rhythms.

Eating Too Late

Your eating habits can have a profound effect on your circadian rhythm and your sleep quality. Anyone who has a large meal immediately before bed will likely find that their sleep is fragmented and anything but restful. That’s because the meal prompts your brain to kick into digestion mode instead of sleep mode. Luckily, there are some light snacks you can enjoy in the evening that should help you get the Zzzs you need.

Exercising Before Bed

Like eating, research has shown that evening exercise can also cause phase delays in your circadian rhythm. The science here is pretty simple — when you exercise, your body releases endorphins. These guys may be great mood boosters during the day, but when they come out to play before bed, they can keep you awake. Moreover, when you pair boosted endorphin levels with spikes in your heart rate, blood pressure, and core body temperature, your sleep (and circadian rhythm) can go off the rails.

Caffeine

Anyone who regularly enjoys a cup of coffee after dinner might want to reconsider. While caffeine can do a bang-up job of getting you over the 2 p.m. slump, study after study has shown that caffeine can delay sleep onset and REM sleep.

When A Circadian Rhythm Should Be Reset

Circadian rhythms are sensitive to disruption and inconsistency. If disruptions are short-lived, the disturbance is likely to be temporary. However, repeated disruptive behaviors can lead to severe circadian rhythm dysfunction, requiring some type of intervention.

“You can shift your circadian rhythm when your sleep/wake schedule has drifted from where you want it,” says Olson. “For example, you might stay up for a few nights on the weekend and find yourself falling asleep too late throughout the rest of the week. Light exposure or exercise in the morning can help you get back on track.”

You might consider shifting your circadian rhythm if you:

Start a new job or school schedule
Are a shift worker or regularly do rotating shift work (law enforcement, hospital, etc.)
Travel across time zones regularly
Consistently use certain medications or drugs
Engage in a new activity with an early morning start time

How To Change Your Sleep Schedule

If your circadian rhythm is offbeat, there are things you can do to get things back on track.

Dim the Lights

“Getting bright light exposure in the morning will shift your body clock earlier so you feel tired earlier,” says Olson. “Conversely, bright light exposure in the evening will push the body clock later, so you feel tired later.” To shift your circadian rhythm in favor of an earlier wakeup, try dimming the lights a few hours before bed. This will send a signal to your brain that bedtime is approaching.

Change Your Meal Times

The circadian rhythm responds to food consumption by priming hormones, enzymes, and digestive systems for activity in the morning and afternoon. Shifting breakfast, lunch, and dinner times an hour earlier or later may help move the body’s internal clock backward or forward.

Exercise Earlier in the Day

Muscles have their own internal clocks, and research has shown that our muscles function better during our waking hours. So, while nighttime exercise tends to promote wakefulness and impair your sleep, daytime exercise is an excellent tool to help you adjust your circadian rhythm. And if you need another “pro” on your list of reasons to work out earlier in the day, studies show that daytime exercise may also benefit general health more than working out in the evening.

Shift Your Bedtime

To fall asleep earlier, try shifting your sleep-wake times until you’re back where you need to be. While this method works well, Olson cautions, “Circadian rhythms should be shifted slowly, usually by around half an hour to an hour per day. If you are going to sleep around midnight and want to sleep an hour earlier, try getting some bright light exposure in the morning (e.g., from sunlight during a morning walk), go to bed at 11:30 p.m. that night, and then go to bed at 11:00 p.m. the following night.”

Try a Nap

According to Olson, while napping is usually frowned upon, it can actually be a helpful tool for those who need to shift their circadian rhythm. “Napping earlier in the day can shift your circadian rhythms earlier; napping in the evening can shift them [later],” he says.

Get Up at the Same Time Every Morning

Later weekend sleep-wake times or an erratic weekday schedule can disturb your circadian rhythm, but consistency is key to keeping your body clock in check. To that end, be sure to maintain consistent sleep and wake times 365 days a year.

Avoid Light Exposure Before Bed

Exposure to artificial light at night can shift your body clock later and throw things off the rails. For that reason, it may be helpful to avoid bright light from any source close to bedtime and dim indoor lights whenever possible.

Don’t Eat Too Close to Bedtime

If you’re catching up on your favorite TV show and snacking while doing so, you might not be in for the smooth night’s sleep you’re hoping for. Eating before bed is likely to activate digestive organs and stimulate the release of insulin and other hormones — all of which will work in concert to keep you awake, further disrupting your circadian rhythm. By focusing on digestion, your body loses its focus on sleep.

To keep things working as they should, Griggs recommends “Avoiding eating two to three hours before bed.” She also notes that while the overnight fast can help your body focus on sleep, heavy meals can “lead to discomfort, worsen acid reflux, and disrupt your ability to fall asleep.”

Try Light Therapy

“Exposure to light at the ‘right time’ can reset a circadian rhythm,” says Griggs. “If people are getting up too early — well before daylight — and feeling sleepy earlier in the evening, adding light exposure at night can help shift them back to a later bedtime. Further, if the person cannot sleep in the morning, keeping the environment dark and wearing sunglasses on a morning walk can help reduce light exposure.”

Griggs tells us that the reverse is also true. Anyone who regularly stays up late and subsequently has a hard time waking up in the morning could try adding more light to their morning routine and dimming their sleeping environment as bedtime approaches.

If you’re thinking about using artificial light for any of the above, Griggs notes that 10,000 lux lamps or light bulbs are ideal for light therapy.

Listening to Your Body: How to Know When It’s Time for Bed

The good news here is that figuring out when it’s time for bed isn’t rocket science — your body will let you know when it’s time to power down and catch your Zzzs. Some common signs that bedtime is approaching are sleepiness, carb cravings, and feeling chilly.

Sleepiness

This one is universal and self-explanatory. If you’re feeling sleepy and even starting to nod off, it might be time to tell Siri to hit the lights and turn in for the night.

Carb Cravings

If you’re hankering for a sugary treat, your body may be telling you that it’s running low on energy. Research has even shown that sleep deprivation can boost hunger hormones (ghrelin) while lowering satiety hormones (leptin). So, you might want to put down the cookie and pull up the covers instead.

Feeling Cold

As sleep time approaches, our core body temperature drops, preparing us for the big snooze. So if you’re feeling a bit chilly, that could be your body giving you the thumbs up for sleep.

Circadian Rhythm Disorders

A disrupted sleep schedule may become severe enough to be considered a sleep disorder. Studies suggest up to 3 percent of the adult population suffers from a circadian rhythm sleep disorder. Read about the most common types below.

Advanced Sleep Phase Disorder (ASPD)

Advanced Sleep Phase Disorder (ASPD) is a disorder where the sleeper has a sleep-wake schedule that is several hours earlier than societal norms. While most people you know may aim to go to bed between 9 p.m. and 11:30 p.m., the onset of sleep for those with ASPD is typically somewhere between 6 p.m. to 9 p.m., and morning wake times are somewhere between 2 a.m. to 5 a.m.

Symptoms commonly associated with Advanced Sleep Phase Disorder include profound late afternoon sleepiness, curtailed evening activities, and a scant social calendar. Bright light therapy is the most common treatment for ASPD.

Delayed Sleep Phase Syndrome (DSPS)

Delayed sleep-wake phase disorder (DSPS) is a circadian rhythm disorder in which sleep is delayed by two or more hours beyond what is socially acceptable. Those with DSPS tend to fall asleep around midnight or later. People with DSPS not only have difficulty falling asleep, but they also have difficulty waking up at the appropriate time.

Common symptoms associated with Delayed Sleep-Wake Phase Disorder are difficulty falling asleep, difficulty waking up, and excessive daytime sleepiness. Typical treatments for DSPS include bright light therapy and chronotherapy.

Chronotherapy Explained

Chronotherapy is used to restore normal sleep-wake cycles, often through timed light exposure and improved sleep hygiene. In some cases, medications or supplements such as melatonin may also be used.

Shift Work Sleep Disorder (SWSD)

Shift Work Sleep Disorder (SWSD) is a circadian rhythm sleep disorder in which a person sleeps on a schedule that’s contradictory to their circadian rhythm due to their work schedule. Nurses, doctors, first responders, and military personnel are prone to SWSD.

Common Symptoms of Shift Work Sleep Disorder

Difficulty initiating sleep
Difficulty maintaining sleep
Impaired alertness
Low energy
Difficulty concentrating
Headaches
Unrefreshing sleep

The circadian shift with SWSD occurs because the person had to be at a particular place at a particular time, which means shift work sleep disorder cannot be “treated” as other circadian rhythm disorders can be treated.

With treatment precluded, management of the disorder is the best way forward for most. In this case, the shift worker is encouraged to maintain strict sleep hygiene off-schedule, the most important aspect of which is strict light discipline (wearing sunglasses once their shift is over and sleeping with blackout curtains). Check out our full guide for sleeping on the night shift here.

FAQ

How long does it take to rewire my circadian rhythm?

“It depends on how much of an adjustment is needed,” says Griggs. “For some, it may take days, others weeks, and based on some studies, it could take months.” Griggs also notes, “Patience with this process is key, as trying to shift by more than one hour per night can affect a person’s daytime function. The body needs time to adjust, and small incremental change is best.”

Can melatonin fix circadian rhythm?

“Some individuals find taking a melatonin supplement can help,” says Griggs. “However, people must be aware that just taking melatonin in it of itself will not always promote sleep at the right time. If the other environmental modifications (dimming the lights, shutting off your screens) are not done, it can still be difficult to fall asleep even with a melatonin supplement.”

How can I fix my circadian rhythm?

You can fix your circadian rhythm by shifting your bedtime, managing your light exposure, and minding your meal times.

The Last Word From Sleepopolis

We each have a biological schedule that plays a significant role in when we feel tired and awake. A well-balanced body clock promotes healthy sleep patterns and the smooth functioning of other bodily processes, such as hunger cues and energy levels.

Travel, work, and stress may make it difficult to maintain consistent sleep and wake times. A desynchronized circadian rhythm can result in sleep deprivation, circadian rhythm disorders, and increased risk for certain health conditions. With healthy sleep strategies in place, we can restore the body’s circadian rhythm and improve health and well-being.

Sources

Gu C, Li J, Zhou J, Yang H, Rohling J. Network structure of the master clock is important for its primary function. Frontiers. July 22, 2021. Accessed May 23, 2024. https://www.frontiersin.org/articles/10.3389/fphys.2021.678391/full.

Wahl S, Engelhardt M, Schaupp P, Lappe C, Ivanov IV. The inner clock-Blue light sets the human rhythm. J Biophotonics. 2019;12(12):e201900102. doi:10.1002/jbio.201900102

Thomas JM, Kern PA, Bush HM, et al. Circadian rhythm phase shifts caused by timed exercise vary with chronotype. JCI Insight. 2020;5(3):e134270. Published 2020 Feb 13. doi:10.1172/jci.insight.134270

Effects of caffeine on the human circadian clock in vivo and … – science. Accessed May 23, 2024. https://www.science.org/doi/10.1126/scitranslmed.aac5125.

Circadian clock interaction with HIF1Α mediates oxygenic … – cell press. Accessed May 23, 2024. https://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30490-9.

Chatterjee S, Ma K. Circadian clock regulation of skeletal muscle growth and repair. F1000Res. 2016;5:1549. Published 2016 Jun 30. doi:10.12688/f1000research.9076.1

Author. 3 ways decreased sleep contributes to overeating. Obesity Prevention Source. September 3, 2014. Accessed May 23, 2024. https://www.hsph.harvard.edu/obesity-prevention-source/2010/01/01/3-ways-decreased-sleep-contributes-to-overeating-2/.

Harding EC, Franks NP, Wisden W. The Temperature Dependence of Sleep. Front Neurosci. 2019;13:336. Published 2019 Apr 24. doi:10.3389/fnins.2019.00336

Advanced sleep phase syndrome. Stanford Health Care (SHC) – Stanford Medical Center. September 12, 2017. Accessed May 23, 2024. https://stanfordhealthcare.org/medical-conditions/sleep/advanced-sleep-phase-syndrome.html.

Delayed sleep phase syndrome (DSPS). Stanford Health Care (SHC) – Stanford Medical Center. September 12, 2017. Accessed May 23, 2024. https://stanfordhealthcare.org/medical-conditions/sleep/delayed-sleep-phase-syndrome.html.

Shift work sleep disorder. Stanford Health Care (SHC) – Stanford Medical Center. September 12, 2017. Accessed May 23, 2024. https://stanfordhealthcare.org/medical-conditions/sleep/shift-work-sleep-disorder.html.