On Your Health

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What Is Your Circadian Rhythm and Why Is It Important?

There are few things better than a good night’s sleep, but many of us struggle to catch enough Zs. If you struggle to fall asleep and wake up at a set time, or catch yourself yawning throughout most of the day, your circadian rhythm could be off.

We’re here to help you understand not only how it works, but how you can get your circadian rhythm back on track for healthy (and regular) sleep. Dr. Jonathan Schwartz of the INTEGRIS Sleep Disorders Center of Oklahoma lends his expertise to help us get to the bottom of the clock that keeps your sleep-wake cycle functioning efficiently.

What are your circadian rhythms?

Your sleep-wake circadian rhythm is an internal clock that runs constantly, cycling between alertness and sleepiness. You may have heard of it as the sleep-wake cycle because it helps regulate sleep patterns.

Circadian rhythms are not solely for humans. Almost all living organisms have circadian rhythms — plants, animals, microbes and more (with a few exceptions). In fact, there is an entire scientific field called chronobiology that is dedicated to studying circadian rhythms.

How do circadian rhythms work?

Our bodies have “circadian clocks” that function in most tissues and organs to regulate timing and circadian rhythms. A master clock keeps each circadian clock and its rhythm running smoothly.

“Many bodily functions operate based on a circadian clock,” Dr. Schwartz says. “Everyday functions – such as sleepiness, wakefulness and hunger – and many hormones function based on a circadian rhythm. The clock maintains the rhythm, so we have ebbs and flows throughout the day, such as being sleepy during part of the day but awake and active for the other part.”

Located in the suprachiasmatic nucleus (SCN) of the brain’s hypothalamus, the master clock receives light signals from the eye’s retina and sends that information to various parts of the brain, including the pineal gland that releases melatonin.

These signals vary throughout the day, which is why your circadian rhythm typically coincides with the sun’s cycle. At night, your SCN receives signals that it’s dark and late in the day. This causes it to send a message to the brain that it’s time to release melatonin, which makes you sleepy. The opposite occurs during the daytime because light signals suppress melatonin production.

It’s common to feel energy dips throughout the day, but it seems many adults feel most fatigued in the afternoons. These dips can vary based on each person’s habits and age.

Circadian Rhythm

How can I maintain a healthy circadian rhythm?

Studies have shown a possible link between healthy circadian rhythms and coordination, cardiovascular activity, cognition, weight control, immune function and digestion. To keep these bodily functions in check, it’s important to develop the following daily habits to support your sleep-wake cycle.

1. Maintain a consistent sleep schedule

Many assume having a set bedtime will keep their circadian rhythm on track. This isn’t the case — it’s also important to wake up at the same time every day. A consistent sleep-wake routine will train your master clock to help you avoid waking up throughout the night. Resist the urge to catch up on sleep after a restless night. It’s common to want to take a long nap or sleep in on the weekends, but this can make your circadian rhythm worse.

Melatonin usually begins triggering the body to rest around 9 p.m. and starts slowing down (which cues the body to wake up) around 7:30 a.m. Try to orient your sleep schedule around these times with extra time for winding down before bed. If your routine is very different from these times, adjust it slowly in 15-minute increments every few days.

2. Get outside in the morning

Exposure to light in the morning triggers your brain to produce less melatonin. The first thing you should do after your alarm sounds is open the blinds. If you have time, get outside and go for a walk or sip your coffee on the porch. Exposure to sunlight will help reset your internal clock for the day.

3. Skip the afternoon nap

Staying active throughout the day can help balance your circadian rhythm by using up your energy stores before prime sleeping hours. “If you are having trouble sleeping, taking a nap can decrease your ability to fall asleep at night,” Dr. Schwartz says. “The longer you are awake, the more your body will want to sleep toward the end of the day.”

Whenever you start feeling a dip in your energy, get up and move around. Many Americans live sedentary lifestyles due to working behind a desk. Give your body some movement and support your circadian rhythm by moving every 30 minutes. This can wake up your body.

4. Avoid heavy meals and caffeine later in the day

What you eat can impact how you sleep. Food and alcohol cause heartburn, and caffeine and nicotine are stimulants that can trigger your brain to keep your body active. Aim to give your body 12 to 14 hours without food to reset (this can include the hours you sleep).

Doing so means your liver won’t be working as hard throughout the night. When your master clock triggers the release of melatonin, it also sends signals to the liver, telling it to stop creating enzymes to turn calories into energy and instead begin storing energy. The more food you put in your body before bed, the harder your liver works, and more food is stored than burned.

5. Limit nightly screen use

We’ve discussed the effects of morning light on your circadian rhythm, and light in the evening works the same way. Household light, from both lamps and blue light emitted from laptops, smartphones and tablets, can trick your brain into thinking it’s still daytime, causing it to suppress melatonin production. “Bright light wakes up your brain,” Dr. Schwartz says.

Start dimming lights about two hours before bedtime and resist scrolling through social media in bed. If you work a night shift or need to use screens in the evenings, you can wear glasses that block blue light or install a blue light filter app on your device.

Maintaining a regular circadian rhythm is crucial for healthy sleep. If daytime drowsiness is interfering with your daily activities, you may have a sleep disorder. Schedule an appointment with the INTEGRIS Sleep Disorders Center of Oklahoma to discuss your symptoms and find a treatment plan to help you sleep better.

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