If I shouldn’t “sleep when I’m dead,” then when should I go to sleep?

The circadian rhythms are controlled by circadian clocks or biological clock. Photo by nambitomo on iStock

We hear so much about mentions of circadian rhythm. But, what is it really? In Latin, circa means almost, and diem means day. Just as how the sun sets and the moon rises, the night begins, and we animals experience biological and hormonal differences, not only in our brains but also in our entire bodies. We sleep! The act of sleeping resets our internal clock. There is an area in the brain called the suprachiasmic nucleus, SCN, in the hypothalamus. It regulates and understands the circadian rhythm by allowing the release of cortisol hormone, also known as the stress hormone, to peak during sunlight hours, transporting us from our dream state to a wake state. In the retina, there are specialized photoreceptors for sky blue, with a frequency of around 500 nm wavelength. These photoreceptors send information to the suprachiasmic nucleus, where our internal clock is established. In the evening during moonlight hours, SCN allows the growth hormone to peak, which is when growth and recovery are at play. This peak time of the growth hormone is around midnight, and to take advantage of it, we need to be asleep. If we miss the period on which the growth hormone is most active, we don’t recover properly; this recovery is for everything, from mental health, brain, muscles, injuries, and anything that may need recovery. Even scars and cuts that may have happened while cooking.

Young woman resting on the couch at home, she is wearing wireless headphones and listening to music. Photo by cyano66 on iStock

Circadian vs. Social Clock

Why is it that even when the time changes, during daylight savings, the time that aligns with when the sun sets switches from one hour to the other semi-permanently, but we still stick to our semi-strict schedule of going to sleep at a certain time range, like 10–11pm? If we are paying attention to circadian rhythm, we should be going to sleep about three hours after sunset. In the summertime, when the sun sets at 7–8pm, going to sleep at 10–11pm should align with our sleep goals. However, in the winter, when the sun sets at around 5pm, 10–11pm is 5–6 hours after sunset. A study by Yetish et al. (2015), was conducted to observe when and how long the pre-industrial societies slept. The data gathered from the three different nomadic societies showed that they sleep for longer periods in the winter, and shorter in the summer, averaging 53–56 min longer in the winter. This discovery could be our guideline to directing us to reserve more sleep time on the days when the average sunlight hours are lower than in the summertime. Simply because there is an unspoken rule of going to sleep at a certain time should not be acceptable throughout the entire year that goes through changes. If our environment is showing changes, we should be as adaptable as we can be to accommodate for the changes.

Smiling man sleeping in a bed covered with dollars money. Photo by tiero on iStock

Millionaire Morning Routines

As we have been exposed from media, such as books and social media, there is a discussion about how millionaires start their day, for the purpose of having peak productivity and focus to carry over throughout the day. Generally, it consists of waking up at 4–5 am. Tim Cook, CEO of Apple, mentioned in a podcast with BBC Sounds that he wakes up between 4–5 am, checks his emails, and works out. Depending on when the sun rises, that is 1–3 hours before the sun rises.

Silhouette of person against sunrise sky. Photo by Ida Rizkha on Pexels

Should we be awakening at or before sunrise?

During the dark hours, there is a continuous melatonin secretion. That is why, the hormone melatonin is also known as the Hormone of Darkness. As the body gets exposed to light, the melatonin secretion decreases to awaken you. Biologically, it makes sense to wake up naturally at sunrise. It is intriguing to note that the three pre-industrial societies mentioned previously averaged awakening before sunset; Tsimane, San, and Hadza communities awakened 1 hour before sunrise, though San society awakenings occurred 1 hour after sunrise in the summer. Based on this research, it is unclear when we should wake up. Of note, On Huberman Lab Podcast #31 with sleep scientist Dr. Matthew Walker, Walker mentions that he usually wakes up a little bit before 7 am. 7 am is when the sun rises in Pacific Standard Time (PST) when daylight savings begins. Dr. Walker begins his day at around sunrise.

Since melatonin release from the pineal gland is dependent on incoming light and is released in the evening hours, it may be a proficient guideline to wake up at sunrise. Why? Because melatonin does wonders for the body when it is at work while we sleep. According to a study by Tordjman, et al. (2017), melatonin improves behavior, mood, development, intellectual function, health, and even seizure control. To let melatonin run its course to give us the maximum therapeutic effects we can carry over to the following day, we should wake up at the time when melatonin secretion decreases through contact with sunlight.

Top view of woman sleeping cozily on a bed at night. Photo by gorodenkoff on iStock

How long should we sleep for?

According to Leavitt (2019), most adults need 1.5–2 hours of deep sleep, with a total of at least 7 hours of sleep every 24 hours. According to James Roland, we need to be sleeping for 5–6 cycles per night, with one cycle being 90 minutes, containing NREM and REM stages. Going back to our when we should sleep and when we should wake up discussion, if the sun sets at 7 pm, we go to sleep 3 hours later, which is 10 pm, and wake up about an hour before sunrise, which is at 6 am (7 am being sunrise), the total duration of sleep time adds up to 8 hours. Sounds ideal, however, make sure to allocate time in your sleep schedule for about 15 minutes to fall asleep.

Top view of young professional tennis player sleeping at his bedroom in sportwear with racket. Photo by master1305 on iStock

Should we sleep longer if we athletically perform?

Should we be sleeping more if we are working out more or active more than usual? Is it more beneficial for our muscle recovery? There have been several studies done with basketball, tennis, and swimmers who have extended their sleep to 9 to 10 hours. The results showed physical and mental improvements in athletes, like their ability to run faster, improved turn times, and increased kick strokes. The athletes reported experiencing improved mood, less sleepiness, and fatigue.

Young man sleeping in bed. Photo by Eren Li on Pixels

How might naps affect overall health?

Does napping mean resting eyes but remaining conscious or falling asleep and waking up after a short amount of time? A nap is a semi-conscious state, where the awakening back to consciousness happens before entering the deeper stages of sleep. Contrary to meditating, which is done while in a conscious state, napping is when you are asleep. A short daytime nap gives better cognitive performance and improved alertness. Naps taken longer than 30 minutes were shown to be correlated with higher frequency of non-alcoholic fatty liver disease, high blood pressure, and increased risk of developing type 2 diabetes.

Friends toasting at table during dinner. Photo by Askar Abayev on Pixels

How can eating affect sleep?

Sleeping occurs due to melatonin release. When melatonin levels are high, insulin secretion is low. Insulin release inhibits melatonin. Insulin will interfere with your sleep. Insulin gets secreted in the presence of glucose, which is when you ingest anything besides water. Since melatonin secretion gradually increases after sunset, it is beneficial to have our last intake of food and caloric or sweetened beverages preceding sunset to accommodate for melatonin to prepare us to sleep for recovery and growth. Stick to eating during daylight hours only.

Young woman awakening in bed in morning. Photo by Miriam Alonso on Pexels

While the research has shown that sleep has numerous benefits, to restarting your system and contributing to growth, recovery, and improvements in mood and mental clarity, it is important to note that the research was done on individuals just like us. Take the research as a guideline, if seeking. Though, it is more important to pay attention to individualistic differences, so, examine your own practices, note what makes you feel better or worse, and create your own guidelines for your specialized routine.

References

1. Nambitomo. (2021, December 29). The circadian rhythms are controlled by circadian clocks or biological clock [Photograph]. Retrieved from https://www.istockphoto.com/photo/the-circadian-rhythms-are-controlled-by-circadian-clocks-or-biological-clock-gm1361759841-434029243?utm_campaign=srp_photos_noresults&utm_content=https%3A%2F%2Fwww.pexels.com%2Fsearch%2Fcircadian%2F&utm_medium=affiliate&utm_source=pexels&utm_term=circadian
2. Bear MH, Reddy V, Bollu PC. Neuroanatomy, Hypothalamus. [Updated 2022 Oct 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK525993/
3. Kolb H. Photoreceptors. 2005 May 1 [Updated 2012 Feb 28]. In: Kolb H, Fernandez E, Nelson R, editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK11522/
4. Cyano66. (2022, January 19). Teenager relaxing on the sofa and listening to music [Photograph]. Retrieved from https://www.istockphoto.com/photo/teenager-relaxing-on-the-sofa-and-listening-to-music-gm1365087908-436063800
5. Thompson Payton, L. (2023, May 13). The best time to sleep for optimal health. Fortune. Retrieved from https://fortune.com/well/2023/05/13/best-time-to-sleep/
6. Yetish, G., Kaplan, H., Gurven, M., Wood, B., Pontzer, H., Manger, P. R., Wilson, C., McGregor, R., & Siegel, J. M. (2015). Natural sleep and its seasonal variations in three pre-industrial societies. Current Biology, 25(21), 2862–2868. https://doi.org/10.1016/j.cub.2015.09.046
7. Tiero. (2021, October 13). Smiling man sleeping in a bed covered with dollars [Photograph]. Retrieved from https://www.istockphoto.com/photo/smiling-man-sleeping-in-a-bed-covered-with-dollars-gm1346182684-424025405
8. Jackson, S. (2023, December 9). Tim Cook’s daily routine reveals the secrets of Apple’s success. Business Insider. Retrieved from https://www.businessinsider.com/tim-cook-daily-routine-schedule-apple-ceo#after-his-workout-and-a-shower-cook-heads-to-starbucks-4
9. Rizkha, I. (2019, July 2). Silhouette of person against sunset sky [Photograph]. Pexels. Retrieved from https://www.pexels.com/photo/silhouette-of-person-against-sunset-sky-3685271/
10. Masters, A., Pandi-Perumal, S. R., Seixas, A., Girardin, J. L., & McFarlane, S. I. (2014). Melatonin, the Hormone of Darkness: From Sleep Promotion to Ebola Treatment. Brain disorders & therapy, 4(1), 1000151. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334454/
11. Huberman, A. [Andrew Huberman]. (2021, August 2). Dr. Matthew Walker: The Science & Practice of Perfecting Your Sleep | Huberman Lab Podcast #31 [Video file]. Retrieved from https://youtu.be/gbQFSMayJxk?si=bvRn45KLkcaDwXmT
12. Tordjman, S., Chokron, S., Delorme, R., Charrier, A., Bellissant, E., Jaafari, N., & Fougerou, C. (2017). Melatonin: Pharmacology, Functions and Therapeutic Benefits. Current neuropharmacology, 15(3), 434–443. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5405617/
13. Gorodenkoff. (2019, June 18). Top view of beautiful young woman sleeping cozily on a bed in his bedroom at night [Photograph]. Retrieved from https://www.istockphoto.com/photo/top-view-of-beautiful-young-woman-sleeping-cozily-on-a-bed-in-his-bedroom-at-night-gm1156679499-315338112
14. Leavitt, J. (2019, October 10). How much deep sleep do you need? Healthline. Retrieved from https://www.healthline.com/health/how-much-deep-sleep-do-you-need#faq
15. Master1305. (2020, October 9). Top view of young professional tennis player sleeping at his bedroom in sportswear [Photograph]. iStock. Retrieved from https://www.istockphoto.com/photo/top-view-of-young-professional-tennis-player-sleeping-at-his-bedroom-in-sportwear-gm1278564514-377461632
16. Mah, C. D., Mah, K. E., Kezirian, E. J., & Dement, W. C. (2011). The effects of sleep extension on the athletic performance of collegiate basketball players. Sleep, 34(7), 943–950. https://pubmed.ncbi.nlm.nih.gov/21731144/
17. Vitale, K. C., Owens, R., Hopkins, S. R., & Malhotra, A. (2019). Sleep hygiene for optimizing recovery in athletes: Review and recommendations. International Journal of Sports Medicine, 40(8), 535–543. https://pubmed.ncbi.nlm.nih.gov/31288293/
18. Schwartz J, Simon RD Jr. Sleep extension improves serving accuracy: A study with college varsity tennis players.Physiol Behav. 2015 Nov 1;151:541–4. doi: 10.1016/j.physbeh.2015.08.035. Epub 2015 Sep 1. https://pubmed.ncbi.nlm.nih.gov/26325012/
19. Li, E. (2021, March 11). Young man sleeping in bed [Photograph]. Pexels. Retrieved from https://www.pexels.com/photo/young-man-sleeping-in-bed-7241262/
20. Christiano, D. (2024, January 10). The power nap: Benefits, tips, and how to do it. Sleep.com. Retrieved from https://www.sleep.com/sleep-health/power-nap
21. Dutheil F, Danini B, Bagheri R, Fantini ML, Pereira B, Moustafa F, Trousselard M, Navel V. Effects of a Short Daytime Nap on the Cognitive Performance: A Systematic Review and Meta-Analysis. International Journal of Environmental Research and Public Health. 2021; 18(19):10212. https://www.mdpi.com/1660-4601/18/19/10212#metrics
22. Summer, J. (2024, March 11). Napping. Sleep Foundation. Retrieved from https://www.sleepfoundation.org/napping
23. Abayev, A. (2020, October 2). Diverse friends toasting at table with candles in garden [Photograph]. Pexels. Retrieved from https://www.pexels.com/photo/diverse-friends-toasting-at-table-with-candles-in-garden-5638816/
24. Chaput, JP., McHill, A.W., Cox, R.C. et al. The role of insufficient sleep and circadian misalignment in obesity. Nat Rev Endocrinol 19, 82–97 (2023). https://www.nature.com/articles/s41574-022-00747-7
25. Alonso, M. (2021, April 7). Young woman awakening in bed in morning [Photograph]. Pexels. Retrieved from https://www.pexels.com/photo/young-woman-awakening-in-bed-in-morning-7622506/