Aiding sleep Part three — circadian rhythm

There are two main chemical mediators which play a major role in our circadian rhythm, our body’s 24-hour internal clock, which controls our sleep-wake cycle; these are cortisol and melatonin. Setting our internal clock and sleep-wake cycle requires daylight exposure (and recognition of night), this regulates melatonin release. Equally, stress and increased cortisol levels will also affect our circadian rhythm. Generations ago people woke with the sun and went to bed near sunset, sleeping time was regulated by natural light. Our ancestors didn’t have artificial light to interrupt the cycle of melatonin levels rising at sunset and dropping over night. Artificial/ LED lights from screens stop the release of melatonin at night.

How to regulate melatonin release?
• This important sleep signalling mechanism can be assisted by being outside, or at the least sitting beside a sunny window, during the morning and afternoon — which harks back to our ancestors natural propensity for sleep as they were up with the daylight and exposed regularly (Pazarci et al., 2020; Oboyashi et al., 2012). At the least, try to be in the most direct sunlight for about 10 minutes per day (roughly the middle of the day). Light therapy boxes can also be useful if getting ordinary daylight is not possible.

• As the sun sets, we should be cautious not to create artificial light via phone, computer, TV screens and harsh overhead lights. Try to be 1.5m away from the TV screen and limit phone/ computer use. Also try blue-blocking glasses or set the monitor display to take out blue light at sunset.

• Create a dark environment for sleeping, use black out curtains and limit any flashing plugged in devices. When light is present during bed time, our optic nerves in the eyes kickstart cortisol levels and reduce melatonin, making the sleep-wake cycle out of whack.

The pineal gland is responsible for melatonin production. To be clear, melatonin doesn’t make us fall asleep like a sleeping tablet can, but as melatonin levels rise in the evening it does help promote a sleepy state. Typically around 2 hours after the onset of melatonin production there is an increase in sleep propensity. Cortisol & melatonin sit at opposite ends of the ‘see-saw’. When cortisol is high & releases in the morning, melatonin is low. Conversely, when melatonin peaks around dusk our cortisol levels are low, or should be.
When either of these are out of balance our ability to sleep is affected.

How to regulate Cortisol?
• As mentioned in my last article, regular meditation practice can help to decrease cortisol. Breathing long and deep as part of meditation is also shown to lower cortisol (Zaccaro et al., 2018).

• Numerous studies also prove that yoga and qi gong (tai chi) can help to reduce stress and the release of cortisol (Riley & Park, 2015; Campo et al., 2014; Zeng et al, 2014; Maddux et al., 2017).

• Regular exercise has been shown to reduce cortisol levels over time, however be cautious of the type of exercise, intensity and length of time. If cortisol is chronically running high, overdoing the exercise will give the opposite effects. Aiming for 150–200 minutes of mostly low-to-moderate intensity exercise is recommended, allow rest in between and no exercise 2–3 hours before intended bedtime (Childs & de Wit, 2014; Dolezal et al., 2017).

• Laughing, having fun and engaging in hobbies that one genuinely enjoys promote endorphins which can help to suppress this stress hormone (Yim 2016; Dunbar et al., 2012).

• Pet therapy (ie. looking after a dog) has been shown to reduce stress and therefore cortisol (Krause-Parello, et al., 2012).

• Increasing Omega-3 fatty acids can help to attenuate high cortisol levels (Delarue et al., 2003; Hamazaki & Itomura, 2000). Linseed, walnuts, pumpkin seeds and dark green leafy vegetables are great ethical sources of omega-3s, along with algae oil.

• Diets high in sugar, refined grains and saturated fats can lead to higher levels of cortisol compared to those high in whole grains, fruits, vegetables and polyunsaturated fats (Soltani et al., 2019).

• Blood sugar issues (Melilo, 2020), sleep apnoea (Tomfohr et al., 2012), plus chronic infections and allergies creating a proglonged state of inflammation can increase cortisol levels (Hannibal & Bishop, 2014). Therefore, addressing these factors may play a major part in the puzzle of sleep disturbances.

Working to balance these two hormones may assist those with sleeping difficulty or insomnia.