The human body undergoes constant development throughout life, yet the need for a stable circadian rhythm remains steadfast. However, our circadian rhythm and sleep patterns undergo significant changes as we age. We gradually retire to bed earlier, sleep for fewer (continuous) hours, and experience a decline in sleep quality. But why does this happen?
Common to all individuals is the fact that our circadian rhythm is designed to follow the sun's rhythm. We are biologically wired to wake up when the sun rises and go to bed when the sun sets. However, it is also common for most people that this rhythm changes throughout life's different phases.
During our teenage years, our circadian rhythm is significantly different from when we reach retirement age. Most of us experience staying up later and sleeping longer as young adults, while as we age, we tend to go to bed earlier and sleep for shorter periods. The quality of our sleep also tends to decline with age, with deep sleep becoming less frequent and light sleep becoming more predominant. The downside of light sleep is the increased likelihood of waking up throughout the night, ultimately affecting our overall sleep quality. Waking up multiple times during the night means missing out on the crucial REM sleep stage, where deep sleep occurs, leading many adults and seniors to feel like they are awake for much of the night.
Studies indicate that sleep issues have become more prevalent over the years. Older adults, on average, sleep much less than younger adults, despite the sleep requirements being fairly similar for both age groups. In fact, over a third of older adults experience waking up earlier in the morning and/or have difficulty maintaining a regular sleep pattern – but there may be a quite natural explanation for this.
Why Does The Circadian Rhythm Shift?
Studies have shown that the circadian rhythm advances with age, and this shift may be attributed to both biological and environmental factors.
On a biological level, physiological processes such as body temperature, melatonin, and cortisol levels undergo changes over time. As we age, our body temperature rises and hormone levels peak earlier in the day compared to when we were young adults. This shift often leads many individuals to find themselves heading to bed earlier in the evening and waking up earlier in the morning as they grow older.
Throughout our lives, light is the most crucial factor in regulating our circadian rhythm. This has led researchers to explore how our exposure to and absorption of light changes as we age. Studies have delved into how the human eye evolves over time, revealing that as we grow older, our eyes struggle to let in light in the same way as when we were younger. This means that our eyes have a harder time 'capturing' light as we age, making it more challenging for our brain to regulate the circadian rhythm 'correctly'. Adding to this challenge is the fact that we predominantly spend our time indoors, where the lighting is often insufficient to begin with, making it even more difficult for the ageing eye to absorb enough light. With over 90% of our time spent indoors, artificial light becomes the primary light source for most of us, which is not ideal. In many indoor settings, artificial light is too dim during the day and too bright in the evening/night compared to natural light conditions, which we are biologically programmed to follow.
What Can You Do to Ensure a Healthy Circadian Rhythm?
It's undeniable that light plays a crucial role in our circadian rhythm, making it essential to ensure we get the right light at the right time. This means plenty of bright light during the day (preferably sunlight), dim to no light in the evening, and complete darkness at night. This is what our bodies are wired for, but it's often easier said than done, especially with over 90% of our time spent indoors. Additionally, it's beneficial to try to go to bed and wake up at the same time every day to establish a consistent routine, which is healthy for both the body and mind. However, maintaining this routine can be challenging for those struggling with sleep issues but there are solutions available. Recently, the Danish Health Authority introduced recommendations for sleep duration (for all age groups) along with a list of tips for a good night's sleep.
How to get a good night's sleep
- Avoid consuming caffeine before bedtime.
- Steer clear of alcohol before bedtime.
- Refrain from indulging in heavy, high-energy, and fatty foods before bedtime.
- Ensure you stay physically active throughout the day.
- Maintain a well-tempered bedroom. The optimal room temperature for sleep is typically between 18-21 degrees Celsius.
- Minimize noise levels in the bedroom to below 30 decibels. Consider using earplugs if needed.
- Limit exposure to screen light (e.g., computers, tablets, and TVs) before bedtime. You can adjust the brightness on most screens.
- Keep the bedroom dark. Consider using an eye mask if necessary.