Circadian Rhythm

As we skipped into March and allowed memories of a long winter and the likes of Storm Eunice to fade away there was a notable uplift in the weather. Milder days became less of a novelty and as we approached the Spring Equinox it was increasingly evident that spring had sprung and longer, lighter days were to be enjoyed.

It may be a cliché to say that everyone is in a better mood when the sun is out, but there is science behind that too. In case you weren’t aware, sunlight exposure, as well as many foods, is a source of vitamin D. We have vitamin D receptors in our pre-frontal cortex (kind of like your brain’s command centre) portion of the brain, the hypothalamus and substantia nigra, which play a part in emotional regulation1. Thereby, with a steady supply of said vitamin D we can similarly expect our emotions to be steadier with less fluctuations. Vitamin D itself regulates serotonin levels in the body, with decreasing vitamin D levels, we can expect decreasing levels of serotonin2. Decreased serotonin levels could then in turn result in decreased mood and at it’s worst depression3.

When we couple this with the contentious Daylight Saving Time change happening in March, we also have a favourable change in our circadian rhythm. Circadian rhythm is a fancy way to describe your body’s inner clock. When we optimise our circadian rhythm, again we can expect a synchronised delivery of helpful hormones to boost our energy4. This circadian rhythm is dictated by light and dark cycles over a 24 hour period5. Over the dark, winter months, it becomes more challenging for the circadian rhythm to synchronise and deliver the helpful hormones and energy we ironically need more of during this season6.

So with this seasonal change, could you consider a concentrated effort in optimising your circadian rhythm further by harnessing the brighter mornings? When we make a conscious effort to stick to a set bed time and wake time we also regulate the circadian rhythm further7. As, simply put, the body knows what it’s doing and when, so subsequently helps you out with the right hormones and energy levels at the right times. Unsurprisingly, this also results in a better sleep quality experienced7, I’m not sure what the opposite to a ‘vicious cycle’ is in colloquial terms, but here is an example of it. With better sleep quality, you’ll have more energy8, improved cognition9 and improved wellbeing10, I could go on…?

If you’re up with the larks you could stand to enjoy further benefits if you do some exercise too. Exercising in the morning has been found to aid with being asleep by an earlier time in the evenings11, another way to guarantee you’re feeling as good as possible the next day!

Sticking to a consistent bed time and wake time is without doubt my favourite health tip. The benefits are huge and personally I just feel infinitely better than when I’m all over the place with my sleep routine. I’m sure a lot of people really want to come back at me with: what about socialising? What about watching a film or series that’s really good? Or I need to sleep in at weekends to catch up. I guess it’s a question to ask yourself, what brings you most happiness and has you feeling good? Is it to hang out at the bar till 1am or to wake at that same time and get cracking with the day? For those that say they need to sleep in to recover, is there something to be said for your midweek routine? If there’s lots of burning the candle and both ends, late nights-followed by early starts for work, then perhaps some readjustment is needed in your lifestyle.

I also get a lot of people saying they’re just not tired in the evenings and this may well be true. We do have our sleep chronotype, or your body’s natural inclination for alertness and activity or tiredness and sleep at different times of the day12 (morning lark or night owl are typical two examples). But again, there is some wiggle room in this and with a good routine you can find yourself consistently being able to make that early alarm, provided you’re doing the right thing at the evening end each day.

Modern lifestyles see people often watching television or using screens (phones, tablets, laptops) late into the evening. This screen use will interfere with sleep duration, quality and cause daytime sleepiness13. To help with securing the early night-early rise cycle, spend a good hour or so away from screens and artificial light before bed. Instead, you could stretch, listen to music or read (remember reading? Entertainment before screens!). I particularly like reading before bed. I tend to rotate fiction, CPD and history or information books that I have an interest in. There’s a quote I like from Anissa Trisdianty who said: “reading is dreaming with open eyes”. There’s definitely something in that, if you’re reading in bed- you’re on that path to sleeping and having a dream, all that’s left is for you to shut your eyes!

Like all things, if you dip your toe in, chances are it’s not going to work for you, ultimately you haven’t exposed yourself to the minimum dosage required for it to take effect. Get up early one morning and you’re tired-shock! So make a conscious effort for a 3 weeks minimum and see if you start to feel better with the early night-early rise routine. I hope you do.

References

1. Eyles DW, Smith S, Kinobe R, et al. Distribution of the vitamin D receptor and 1 α-hydroxylase in human brain. J Chem Neuroanat. 2005;29(1):21-30.

2. Patrick RP, Ames BN. Vitamin D and the omega-3 fatty acids control serotonin synthesis and action, part 2: relevance for ADHD, bipolar disorder, schizophrenia, and impulsive behavior. FASEB J. 2015;29(6):2207-2222.

3. Delgado PL. Depression: the case for a monoamine deficiency. J Clin Psychiatry. 2000;61(suppl 6):7-11.

4. Dickmeis, T., 2009. Glucocorticoids and the circadian clock. Journal of Endocrinology, 200(1), p.3.

5. Challet, E., 2015. Keeping circadian time with hormones. Diabetes, Obesity and Metabolism, 17, pp.76-83.

6. Hadlow, N.C., Brown, S., Wardrop, R. and Henley, D., 2014. The effects of season, daylight saving and time of sunrise on serum cortisol in a large population. Chronobiology international, 31(2), pp.243-251.

7. Monk, T.H., Petrie, S.R., Hayes, A.J. and Kupfer, D.J., 1994. Regularity of daily life in relation to personality, age, gender, sleep quality and circadian rhythms. Journal of sleep research, 3(4), pp.196-205.

8. Steffen, M.W., Hazelton, A.C., Moore, W.R., Jenkins, S.M., Clark, M.M. and Hagen, P.T., 2015. Improving Sleep. Journal of occupational and environmental medicine, 57(1), pp.1-5.

9. Fulda, S. and Schulz, H., 2001. Cognitive dysfunction in sleep disorders. Sleep medicine reviews, 5(6), pp.423-445.

10. Hamilton, N.A., Nelson, C.A., Stevens, N. and Kitzman, H., 2007. Sleep and psychological well-being. Social Indicators Research, 82(1), pp.147-163.

11. Saidi, O., Colin, E., Rance, M., Doré, E., Pereira, B. and Duché, P., 2021. Effect of morning versus evening exercise training on sleep, physical activity, fitness, fatigue and quality of life in overweight and obese adults. Chronobiology international, 38(11), pp.1537-1548.

12. Merikanto, I., Kronholm, E., Peltonen, M., Laatikainen, T., Lahti, T. and Partonen, T., 2012. Relation of chronotype to sleep complaints in the general Finnish population. Chronobiology international, 29(3), pp.311-317.

13. Mak, Y.W., Wu, C.S.T., Hui, D.W.S., Lam, S.P., Tse, H.Y., Yu, W.Y. and Wong, H.T., 2014. Association between screen viewing duration and sleep duration, sleep quality, and excessive daytime sleepiness among adolescents in Hong Kong. International journal of environmental research and public health, 11(11), pp.11201-11219.