Effects of Aging on Your Biological Clock

Your circadian rhythm is basically your body’s internal clock, guiding the natural 24-hour cycle of sleep, wakefulness, and a variety of physiological processes. (1) It’s controlled by a group of genes known as "clock genes," which orchestrate the timing of various biological functions. (2) In fact, your circadian rhythm keeps everything from metabolism to hormone levels and DNA repair in sync, ensuring that they happen exactly when they’re supposed to.

For example, your body burns calories more efficiently during the day when you’re most active and then shifts to rest mode during the night. Hormones like cortisol and insulin follow this rhythm too, controlling energy, stress levels, and blood sugar balance. (3) On top of that, your circadian clock plays a key role in DNA repair, working behind the scenes to coordinate repair efforts when cell activity slows down at night.

Age can have a big impact on your body’s biological clock, which can also impact your overall health. One of the main disruptions is a drop in the production of melatonin, leading to erratic sleep patterns that can interfere with these vital repair processes. (4, 5) Weakened clock gene expression and circadian signal strength due to aging can also cause your internal clock to fall out of sync with your environment, leading to disruptions in metabolism, hormonal imbalances, and a decline in your body’s ability to repair DNA and maintain health. (6)

How Light Sets Your Circadian Clock

Aging can decrease your sensitivity to light, leading to a serious shift in your circadian rhythm. In fact, older adults often struggle with sleep, dealing with more nighttime wakings, earlier sleep and wake times, and interrupted sleep throughout the night. (7)

Sunlight is one of the most powerful factors that can help regulate your body’s internal clock by boosting the production of melatonin, a hormone that helps signal when it's time to sleep. Exposure to bright, natural light (especially right when you wake up) can reset your circadian rhythm, improving your circadian alignment and ensuring that you’re able to get plenty of rest at night. (8) This is backed by a 2023 study in Journal of Sleep Research, which found that exposure to morning sunlight led to improved sleep efficiency and better sleep outcomes in college students. (9)

Try opening up the windows after you wake up, eating breakfast outside, or going for a morning stroll to soak up some sun. If you’re getting up before sunrise or stuck in gloomy weather, bright light therapy using a light box might work instead.

The Role of Sleep in Repair and Recovery

As you get older, sleep becomes even more important for your body’s recovery processes. While you sleep, your body focuses on healing, repairing damaged tissues, strengthening muscles, and neutralizing any oxidative stress and inflammation that has accumulated during the day. (10) But over time, your sleep quality tends to dip, slowing down your body’s built-in repair processes and increasing the risk of age-related health issues. 

Aiming for a solid 7-9 hours each night can help support these essential repair processes, while also strengthening your body’s circadian clock in the process. (11, 12) It can also promote better alignment with external cues (such as sunlight), which can boost sleep quality, promote cell repair, and maintain metabolic equilibrium. (13) Set yourself up for better sleep by keeping your bedroom quiet and dark, ditching screens a bit before bedtime, and cutting out caffeine later in the day. (14)

How NAD+ Supports Circadian Rhythms and Mitochondrial Function

Not only do mitochondria power the cells throughout your body, but they also sync your circadian rhythm and keep things running smoothly by influencing energy production and metabolism. More specifically, they help regulate levels of nicotinamide adenine dinucleotide (NAD+), a coenzyme that controls the activity of sirtuins and other proteins needed to maintain your body's internal clock. (15)

Over time, NAD+ levels naturally decline, which can contribute to mitochondrial dysfunction. (16) In addition to impacting energy production, this can also throw your circadian rhythm out of whack, making it harder for your body to maintain metabolic balance and regulate sleep-wake cycles. (17)

NAD+ precursors like nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) can help boost NAD+ levels, which in turn supports mitochondrial function. (18) Healthier mitochondria can also promote energy production, cell repair, and metabolism, all of which are key for keeping your circadian cycle aligned. (15) For best results, take NAD+ precursors earlier in the day. Not only does this line up best with your body’s natural rhythm, but it may also help support energy and metabolism during the day and set you up for better sleep later on. (19)

Conclusion

 

Your circadian rhythm plays a central role in metabolic health, hormone balance, and cell repair, especially as you get older. Even though disruptions in your internal clock can cause issues, simple lifestyle changes like morning sun exposure, healthy sleep habits, and targeted supplementation can help restore alignment. By prioritizing these practices, you can keep your body’s circadian clock in sync and promote better long-term health.