Welcome to September!
I hope everyone had a wonderful, relaxing summer! I had the opportunity to hike many of our amazing National Parks, what a treasure they are! Hiking provides my bones and my body with vital exercise and communing with nature revitalizes my soul. And boy did I sleep well at night! There is nothing better for your body and your brain than a good night’s sleep. But did you know that your bones benefit from a good night of slumber as well? While you’re fast asleep, your bones are hard at work sloughing off the old, worn out cells and forming strong, new cells. However, lack of sleep or disruption of normal sleep patterns can affect bone remodeling, leaving people who suffer with insomnia or circadian rhythm disturbances are at an increased risk for bone loss and bone fractures.
How Does Sleep Happen?
Sleep is dictated by 2 processes in the body. Process-S which stands for sleep-wake homeostasis and Process-C, your circadian rhythm. Today we are going to focus on Process-C and how the circadian rhythm impacts bone remodeling.
The circadian rhythm is the body’s internal clock that is designed to regulate the sleep-wake cycle over a 24 hour period. It is also responsible for regulating body temperature, metabolism and the release of several hormones, like melatonin. Disruption in the circadian rhythm has been shown to contribute to the development of cardiovascular disease, cancer, metabolic syndromes, aging, and new evidence suggests it can impact bone remodeling as well. Studies suggest that disturbances of circadian rhythms by social or environmental factors may result in loss of bone mass and increased risk for fractures.
- In the Nurses’ Health Study, long durations of rotating night-shift work was associated with an increased risk of wrist and hip fractures
- Long term light exposure, disturbing the daily rhythm of light and dark, reduced bone mass in mice
- 3 weeks disruption of the sleep/circadian rhythm resulted in a decrease in bone formation, but no change in bone resorption. This negatively affected bone remodeling and creating the potential for bone loss
Light is the Major Driver of the Circadian Rhythm
Light stimulates a nerve pathway from the retina in the eye to a special area in the hypothalamus of the brain called the suprachiasmatic nucleus (SCN). The SCN signals to other parts of the brain that control hormones, body temperature and other functions that play a role in making us feel sleepy or wide awake. Morning sunlight excites the SCN to begin performing functions like raising body temperature and stimulating cortisol to wake us up and get us ready for the day ahead. At the same time, it inhibits the release of melatonin, the hormone that tells your body when it’s time to sleep. As the sun sets, melatonin levles gradually begins to rise making you feel sleepy and yearn for bed. Melatonin levels remain elevated through the night and then drop off with the light of a new day.
Beyond initiating sleep, melatonin has several other beneficial roles in the body, including supporting immune function and proper bone metabolism. Low levels of melatonin at night have been correlated with an increase in bone resorption and osteoporosis.
Because light is a direct inhibitor to the production of melatonin, exposure to light at night, can affect melatonin levels. Especially exposure to blue light emitted from our phones, computers, pads, and energy-efficient lighting. Although the light from the sun contains rays of all colors, it is the blue light that gives us energy and regulates our circadian rhythm. So excessive use of our electronic devices at night signals to our SCN that it is daytime. This disrupts our body clock, and halts melatonin production. The result? Poor sleep, inadequate bone remodeling and diminished overall health.
The bottom line: Sleep is essential for normal bone remodeling and we need to honor our body’s natural circadian rhythm for quality sleep and optimal health.
If you follow your body’s natural cues regarding when to go to sleep and wake up, as well as avoid blue light at night and get plenty of daytime sunshine, your body clock will continue ticking with accuracy.
Tips to Keep your Body Clock Ticking on Time
Here are a few tips to keep your circadian rhythm functioning the way nature intended:
- Stick to a Consistent Sleep Schedule 7 days a week. Going to bed and waking up at the same time every day will help keep your circadian rhythm in balance. Staying up late to finish a work project and thinking you can make up for lost sleep by sleeping in late on weekends will only disrupt your body’s natural clock.
- Get Outside in the Sun. Exposure to daylight will signal to your brain that it is daytime and solidify the circadian rhythm. Sunshine is also the best way to boost your vitamin D levels. Vitamin D deficiency has also been linked to poor quality sleep.
- Limit Evening Tech Time. Blue lights in the evening hours can throw off your body clock by confusing your brain into thinking it’s still daytime. The blue light from phones, laptops, pads is the worst culprit, so power-down your devices at least two to three hours before bed.
- Keep your Bedroom Cool and Dark. Sleep happens best when you are in a dark, cool environment. Remove as many light sources as possible from your bedroom and aim for a sleeping temperature between 65-69 degrees.
- Don’t Eat Too Late. Timing of food consumption affects the circadian rhythm. Try to have your last meal by 6 or 7 at night. That will give your body 12-14 hours to rest and restore. Your body clock is designed to burn calories during the day and then restore and repair during the night.
The better in sync you are to your body’s internal clock, the stronger your bones and the healthier your mind and body. Your body can overcome a few nights of poor sleep here and there, but consistent disruption in the circadian rhythm can cause long-term health issues, including osteoporosis.