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Are you an early bird or a night owl?

Although some of us think we don’t need much sleep and are sometimes even proud to boast how little we get, the reality of how much we need is very different. According to multiple studies the average adult needs between seven and nine hours of sleep while a senior requires between seven and eight hours1. Many of us understand the value of sleep, however some underestimate the importance of not just sleep quality but also the length of our circadian rhythm (the sleep wake cycle).

Circadian rhythm was discovered in the early nineties. Scientists discovered that circadian disruption could have a significant impact on people’s health. Human sleep genes (“clock” genes discovered in early 21st century) were thought to have an impact on the control of the human metabolic rate and immunity.

The rising and the setting of the sun interacts with the eye (via photosensitive cells which are sensitive to light) and Master Clock (Suprachiasmatic Nucleus) genes in the brain which then send various signals to control other functions of the body such as: temperature, food intake and hunger2. Other peripheral circadian clocks are located in the liver, lungs and heart and regulate the behaviour of these organs and their individual circadian rhythms3.

There are two key groups of Master Clock genes (PER, CRY), the night-time (linked to darkness and sleep) which help to promote melatonin production and daytime (CLOCK, BMAL1) which help to degrade night-time genes and help us to function during the day4. Conversely the daytime genes also activate PER and CRY to promote the build-up of night-time genes during the day to allow sound sleep and melatonin production at night. Early morning light exposure can re-set the circadian rhythm allowing people to sleep well at night. Sufficient exposure to light earlier in the day will also allow more melatonin to be produced at night-time.

We all have different durations of circadian rhythm. Some of us are early birds more likely to be aligned to the light/dark cycle (waking up with the Sun and falling asleep at dusk) and some are night owls (go to bed late but wake up early) with a longer than 24h circadian rhythm and delayed sleep onset and earlier wakening.

Night Owls are more likely to experience sleep deprivation which in the long run can affect their mood, trigger weight gain (due to for example eating too late) and sleepiness during the daytime. An insufficient amount of sleep can impact the production of hormones (leptin and ghrelin)5 which control our appetite and stimulates the secretion of human growth hormone (GH). People with longer circadian rhythms (Night owls) are more likely to respond to signals in more dysfunctional ways resulting in overeating or eating in an unregulated way. Studies suggest that sleep deprivation may reduce the insulin sensitivity and glucose metabolism resulting in weight gain6.

Melatonin also plays a role in weight loss and blood sugar control. Recent studies suggest that melatonin encourages weight loss by utilising energy-burning “beige fat” – fat cells which are located near the collarbone and along the spine in adults7.

This could potentially have a therapeutic effect at treating obesity and diabetes 2. Melatonin has also been linked to blood glucose and blood pressure management.

Different circadian rhythms can have an impact on out eating routine but also our performance levels and the times of the day where we are at our best. Peripheral clocks can be re-trained not only by light but also by the environmental inputs and the regularity of events (for example regular mealtimes or bedtime routine).

By improving our “sleep hygiene” practices (using an eye mask, reducing the light in the room with thick curtains such as black out) and going to bed at regular times we can gradually help to re-train our circadian rhythm and allow night-time genes to activate in anticipation of sleep.

Daily activities such as light exercise can also help to build up Adenosine which inhibits Dopamine (excitatory hormone) and causes sleepiness in the run up to bedtime8. Following a sedentary lifestyle where we don’t produce enough of Adenosine can also be a contribution to dysfunctional circadian rhythm. Caffeine can also inhibit the action of adenosine and increase the activity of dopamine which results in wakefulness and disturbed circadian clocks. It is suggested that even low doses of caffeine may have an effect on the circadian cycle and in some cases keep us alert and awake during the night. It is therefore recommended that caffeine is consumed during the day, in small doses and not just a few hours before going to bed. Daylight and artificial light emission (blue light: mobile phones, tablets, TVs, and computers) may also decrease the production of melatonin. Avoiding digital screens an hour or so before bedtime can help our bodies to wind down.

We can also support the steady production of melatonin by including good sources of certain amino acids such as Tryptophan (precursor in melatonin production)9 found in eggs, salmon, nuts and pumpkinseeds, turkey, cheese, pineapples which is one of the components required to make melatonin and sleep promoting minerals such as Magnesium contained in: green leafy vegetables, raspberries, figs, peas, broccoli’s, artichokes, quinoa, asparagus, cabbage, raw cacao, dark chocolate, seafood (salmon, tuna) and brown rice.

Incorporating a good source of food that naturally contains melatonin may also benefit a good night’s sleep. Good sources include sunflower seeds, walnuts, tomatoes, sour cherries, tart cherry, strawberries, black olives, cardamon and coriander.

Have a good sleep!

Magdalena Marvell is a Nutritional Practitioner and Founder of the Persea Clinic which helps support clients who want to optimise their health in areas such as gut health, hormonal balance, skin conditions, weight management, family nutrition. To find out more about her work please visit




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