Timing is everything. And your body has its own internal clock that will either work for you or against you. Biological rhythms are like a dance on the inside. Changing in waves of movement. Get them wrong and you’ll step on your own toes. Get them right and you will flow through life with enjoyment. Biological rhythms can be used on purpose to improve performance and mood. Or if misunderstood, can lead unintentionally to problems with energy and health.
Not to be confused with biorhythms, biological rhythms or biological clocks control our lives in measurable and repeating ways. The best-known biological rhythm is the circadian rhythm.
Biorhythm theory on the other hand., states that our lives are significantly affected by rhythmic cycles of exactly 23, 28 and 33 days. Comprising a 23-day physical cycle, a 28-day emotional cycle, and a 33-day intellectual cycle. This idea, although very popular especially last century, has been tested and found not to be accurate. So that concept will not be covered here.
The main five biological rhythms
Biological rhythms/clocks that control body and mind functioning in different ways can be broken down into the following:
Ultradian rhythms: Occurs over a shorter time than 24 hours
Diurnal rhythms: Day and night rhythms (often considered part of circadian rhythms)
Circadian rhythms: Occurs every 24 hours
Infradian rhythms: Occurs over a longer time than 24 hours
Circannual rhythms: Occurs over a year
What controls biological rhythms?
Most of our biological rhythms have had their area of control identified. Others have evidence and strong speculation but are unproven. The circadian rhythm for example, is controlled by the Suprachiasmatic Nucleus (SCN). This is a group of cells in a part of the brain called the hypothalamus that responds primarily to light and darkness. Biological rhythms are regulated internally by endogenous pacemakers (biological clocks), and externally by exogenous zeitgebers. The SCN is believed to be a sort of master clock. It is the main endogenous pacemaker and controls most other biological rhythms. Endogenous pacemakers are internal biological clocks, but they can be altered by the environment. The environment falls under the category of exogenous zeitgebers (who comes up with these names?). An example of which is light., which research shows is needed to reset the circadian rhythm cycle every 24 hours. Exogenous zeitgebers can include social activities, medication, and stress. But the most important one is light. Light is responsible for resetting the body clock each day, keeping it to a 24-hour cycle.
Circadian rhythms – your body clock
Let’s start with circadian rhythms., the best known of our biological rhythms. How we live has made the subject of circadian rhythms an important one. Also known as our body clock., circadian rhythms operate on an approximate 24-hour cycle. During those 24 hours, the levels of certain hormones change. The three main ones being serotonin, melatonin, and cortisol. Natural Serotonin levels are usually highest in the morning. Natural melatonin levels are highest at night. Cortisol, although considered a stress hormone, also plays a role in alertness and this also fluctuates during the day. And light (or the lack of light), is the main facilitator of these maintaining the 24 hour cycle. Other changes during this circadian rhythm include changes in core body temperature and the speed of metabolism.
The subject of light is why we know more about the circadian rhythm than any others. Because we have extended our exposure to light way beyond what nature intended.
Sleep wake cycles
What this means is that your circadian rhythm is responsible for your sleep wake cycles. It controls when you feel alert and when you feel sleepy. As you would expect, you are naturally more alert and awake in the mornings., and sleepier and more prone to sleep in the evenings. Historically., and I mean over 100 years ago now., this was controlled by sunrise and sunset. As the sun rose, we would become alert and then the sun itself would help our bodies produce serotonin. Serotonin is known as a feel-good hormone. Not only does it help you feel more alert, but it also boosts your mood. This is why anti depression drugs try to modulate serotonin levels. And it is also why many recreational drugs feel good to take them. Because one of feel-good chemicals they boost is serotonin.
Then as the sun set, much of that serotonin got converted into melatonin. Melatonin is known as the sleep hormone. It is what prepares you for sleep. Bodily function slows down, your core body temperature cools, and your brain activity slows down.
Biological rhythms and artificial light
This is where artificial light becomes a problem for our sleep wake cycles and biological rhythms. Our habits of working and living more and more inside don’t help either. In fact, in some countries during certain times of year., people go to work in the dark and come home in the dark. They don’t see any natural light for months. And then when they do get home, artificial lights are often on late into the night. What does this do to our circadian rhythm? It confuses it and often shifts it to operate at different timings. The result? People can’t get to sleep, or stay asleep, they wake up too early, or they wake up still tired. We have created artificial sunrises and sunsets. And this interferes with our ability to sleep deeply at night and/or be alert during the day. Without the right type and amount of light we are limited to how much serotonin we can produce. And this leaves less to be converted into melatonin at night. And without the right amount of darkness before sleep, the timing of melatonin is delayed. The result of both factors means we are too alert at bedtime and too sleepy during the day.
Circadian rhythms in babies and teenagers
On average adults need about 7-8 hours of sleep a night and have a typical pattern of wakefulness and tiredness as outlined below.
Babies don’t develop a circadian rhythm until they are 2-3 months old. And the levels of melatonin and cortisol continue to develop up until about 9 months old. Which explains the erratic sleep habits in those months. Once established, children on average need about 9-10 hours of sleep a night.
Teenagers need about the same amount of sleep as younger children. Teenagers also have a different circadian timing to both young children and adults. It tends to phase shift to be delayed. This means that teenagers will get tired later at night and need to sleep in longer in the morning. Sometimes a point of frustration (perhaps due to not knowing this) for their parents.
Adjusting your body clock – how it works
4am in the morning is the approximate pivot point for adjusting your circadian rhythm. Light experienced in darkness hours before 4am will tend to delay your circadian rhythm. IE: Phase shift it to later. That means that if you are in bright light late at night or in the early hours of the morning, your whole 24-hour cycle will shift. It will become harder to get to sleep around the 10pm sweet spot, and harder to be alert and focused during a normal 8am to 5pm workday. 10pm, is experimentally the best time to go to bed and ride the wave of increasing melatonin for most people. 10pm seems to be when we are at our maximum sleep need even though melatonin continues to rise.
Light experienced after that 4am point will tend to advance the circadian rhythm. IE: Phase shift it to earlier. How do you use this information? Read on…
This is the average 24-hour circadian rhythm cycle
Around 4am (and accelerating at about 6am) alertness starts to increase in preparation for sunrise. Maximum alertness is at about 10-11am. We have a slight dip in alertness around mid-afternoon or after lunchtime. Then alertness rises to another peak around 6-7pm. And from there (accelerating from about 8pm) our levels of alertness drop and the need for sleep increases peaking at about 10pm. And this pattern then repeats again at 4am. In practice what this means is that the ideal sleep wake cycle is to be awake from about 6am till 10pm.
Early birds and night owls
Some people are naturally night-time people who get up late and go to bed late. There are conflicting arguments as to whether this is healthy long term. Because this habit goes against the internal biological controllers. Other people get up very early and have an early bedtime. This habit is closer to how our ancestors lived. Studies have shown how the body’s circadian rhythms continue even in total darkness. Even without any light, individual rhythms change only slightly from a 24-hour cycle. Circadian cycles range on average between 23.5 hours and 24.6 hours. These differences are due to personal chronotypes. Resulting in people being referred to as either an early bird or a night owl. Jet lag is one example of a rapid change in location confusing the circadian rhythm. In this case the best practice is to get up early in the new country and get early sun exposure.
Shifting your circadian biological rhythm on purpose
It’s clear that artificial light and a lack of sun can shift your body clock unintentionally. As can changing location and therefore sunrise and sunset times. What about changing your biological circadian rhythm on purpose? How do you shift your circadian rhythm to help with sleep and alertness?
Assuming your intention is to be active during daylight hours, then the solution is quite simple. Light experienced after 4am will tend to advance your circadian rhythm. IE: Shift it to earlier. That means if you get early light after 4am and ideally before about 8am, you can shift the 24-hour cycle to be alert earlier and sleepy earlier. Which in practice is how you normalise an out of sync body clock. If you are having trouble sleeping and/or being alert during the day., chances are it’s because your circadian rhythm is delayed. So, the solution is twofold. Firstly, you need to get up earlier and get some bright light. Preferable outside. Secondly, you need to limit or adjust the amount and type of light that you get in the evening. At first getting up earlier will be a challenge. But once you get used to it your sleeping habits and alertness will improve dramatically. It doesn’t have to be 4am. Aim for about 6-7am if you can. Even 8am getting outside in the sunlight will be a huge plus for you if sleep is an issue. 20 minutes of natural light is enough to see significant improvement.
Limiting light at night
How do you limit light at night and still have a life after work? This is about creating healthy averages. Have late nights if you want to. Just be aware of how to maintain peak alertness and the ability to sleep. The next day needs to go back to the ‘early to rise early to bed’ routine. At night try to have at least the last hour before bed in low light conditions. The type of light is also important. By type I mean colour temperature. The two variations most available being warm white or cool white. The end of the light spectrum that has the biggest effect on suppressing melatonin is the blue end. Warm white light has less of this blue light in it. Therefore, by using warm white light bulbs (widely available in stores), you can minimise the impact of late-night lighting. Especially in your bedroom! Another option is to wear blue blocking glasses at night and/or use blue light blocking APPs on your phone and computer. Do yourself a favour however and put the phone to sleep at least an hour before you intend to sleep.
Getting a better night’s sleep is a big subject. And I have written a three-part series on sleep improvement that will give you many ways to improve your sleep.
Read the better sleep series here:
>>>> The better sleep series- volume one >>>>
A subset of circadian rhythms is sometimes called diurnal rhythms. This biological rhythm is synchronised to the day/night cycle although it don’t always follow the same patterns as circadian rhythms. Diurnal rhythms don’t get much focus, but some studies show the potential to use these day/night patterns in interesting ways. An example of where this becomes useful is in the timing of medication or even supplements. One particular diurnal rhythm has a significant effect on arthritis and asthma. And this is the production of certain pro-inflammatory chemicals. The diurnal nature of these results in a rise in pain and discomfort in the morning. Regulation of this pro-inflammatory response has potential therapeutic uses. By monitoring these diurnal patterns, researchers suggest changing the standard schedules of medication to a small late evening dose. The resulting suppression of pro-inflammatory chemicals could reduce early morning inflammation and minimize side-effects. Correlations have also been found between diurnal rhythm disfunction and diseases like Alzheimer’s. Another example is the diurnal nature of certain cancer cells. Breast cancer for example is more active and spreads faster during non active periods and sleep. Potentially leading to more accurate ways to diagnose, monitor, and treat such diseases.
Diurnal rhythms and inflammation >>>
Diurnal and seasonal rhythms in Alzheimer’s >>>
Breast cancer more active at night >>>
Ultradian rhythms – Cycles within cycles
We’ve just shown that circadian rhythms dictate how alert or tired we feel during a 24 period. And that this pattern is predictable and changeable.
What about cycles that happen more often than every 24 hours?
This is where Ultradian biological rhythms come in to play. Ultradian rhythms don’t get as much focus as more commonly discussed circadian rhythms. Ultradian rhythms are a little more frequent and progress in wave like patterns.
Understanding these rhythms can provide you with ways to maximise your health also. Part of this is knowing when you can push yourself and when to give yourself a break.
Nightly sleep cycles – the changing levels of sleep
The most common ultradian rhythm is what happens during a typical night’s sleep. Sleep comes to us in waves of different levels. And the timing of these stages is on average about 90 minutes. IE: it repeats every 90 minutes. There are on average 4 stages of sleep during this 90-minute period. 5 were originally identified but recent findings point to 4 being more accurate. And there are two main qualities of sleep in those stages. Those being REM sleep and non-REM (NREM) sleep. REM stands for rapid eye movement because this is a very active brain stage of sleep that typically makes the eyes flutter. This is due to this stage of sleep being the most active for dreams and memory processing. In fact, the brain uses as much if not more energy during this stage of sleep as when you are awake. We go through about 4-6 of these 90 minutes cycles each night. The early ones tend to be a bit shorter and the later ones a bit longer. And this changes from night to night and person to person.
The four stages of sleep
Stage one N1: NREM (1-5 min) – Dosing off but easy to wake. The body and brain begin to slow down. Small body twitches.
Stage two N2: NREM (10-60 min) – Temperature drops, breathing and heart rate slow, and twitching stops. The brain slows but has bursts of activity that help resist being woken up. This stage tends to get longer as time progresses. Collectively we spend about half our sleep in this stage.
Stage three N3: NREM (20-40 min) – Deep sleep., also known as Delta sleep as brain activity slows to Delta slow wave activity. Harder to wake someone up. This stage is critical for restoration, recovery, and growth. It also is where brain detoxing, and immune system function is boosted. Creativity and memory are consolidated here along with the next stage of REM sleep. This stage tends to get shorter as time progresses.
Stage four: REM (10-60 min) – Increased brain activity. Rapid eye movements. Sleep paralysis occurs here to stop us acting out dreams. REM sleep is believed to be an integral part of maintaining cognitive functions like learning, memory, and creativity. Most vivid dreams occur here. Normally, REM doesn’t start until you’ve been asleep for about 90 minutes. Over time, REM stages get longer. The first REM stage may last only a few minutes. Later stages can last an hour. In total, REM makes up around 25% of sleep (in adults).
Changing your Ultradian sleep cycle biological rhythm
There aren’t many occasions that you would want to change this cycle on purpose. However, there are good practices to ensure that you get enough of each stage. As each of these cycles lasts about 90 minutes., it’s a good idea to sleep in multiples of 90 minutes. So, in practice this means either 6 hours, 7.5 hours or 9 hours. There is enough evidence to suggest that sleeping too long is almost as unhelpful to your health as sleeping too short. Aiming for that 7.5-hour number is a good goal for most people. Alcohol tends to reduce the amount of time in REM sleep so should be limited. Other drugs can do the same thing leading to a lack of quality deep sleep. Even sleeping medications can interfere with this balance and lead to both dependency and cognitive challenges. Any such medication should be done with a doctor’s advice and only used short term.
Consistent bedtimes, a healthy diet, and a good sleeping environment will ensure your sleep cycles stay regular.
How to take a power nap
Why is it recommended to try and keep your total sleep time close to multiples of 90 minutes? This is so that you get a balance of all the stages of sleep which all have health benefits. And there’s another reason too. Have you ever set an alarm to get up early, and then felt tired and struggle to get up? If you force yourself to wake up during the middle of a deep sleep phase, you will tend to feel groggy and unfocused. And this feeling can stay with you keeping you feeling unrested all day. The same applies to taking a nap. If you let the nap go too long, you will fall into a deeper sleep stage. And then unless you sleep for the full 90 minutes, that nap could have you feeling worse than before you took it.
The solution then, is to take naps that go no longer than 30 minutes. Ideally about 10-20 minutes. This will stop you going too deep and will result in the nap making you feel rested and refreshed. The easiest way to do this is to of course set an alarm for 20 minutes. As you get used to this practice, the alarm won’t be needed. You will naturally open your eyes at the right time. The mind gets used to your intention and wakes you up. It is recommended to not take naps after about 3pm to avoid this interfering with your sleep that night.
Ultradian rhythms during the day
The sleep wake cycle is the best known ultradian rhythm but certainly not the only one. Ultradian biological rhythms have also been reported and studied for body temperature, carbon dioxide production, oxygen consumption, blood pressure, hormone secretion, bodily excretion, and digestion to name a few. In science literature ultradian rhythms are loosely defined as periods of time between 20 minutes and 6 hours. More frequent rhythms like brain and heart activity are generally not included in this set of rhythms. Body temperature for example, has some common timings with most animals and humans. The intensity of the peaks of the up and down nature of body temperature and many of the Ultradian rhythms approximately follow the 24-hour circadian rhythm. Most of these ultradian rhythms are less predictable than the circadian rhythm. However, when you look at graphs of the frequency of peaks and troughs during the day., a pattern emerges that seems to be close to the 90-120 minute timings of the phases of sleep. This raises a question…
Ultradian rhythms and productivity
Why is it that during the day we sometimes get to a point where focus gets more challenging? Is it just that we are tired from working? Or does the fact that it usually happens around the same time give us a clue? Due to the difficult nature of accurately studying these more erratic rhythms, the answer is not a definitive yes. However, it has been shown that removing outside influences like light, food, stimulation etc does not have a significant effect on these rhythms. This proves that they are controlled at the cellular level. And are therefore biological and not man made. Experimental evidence suggests that several physiological processes such as arousal, body temperature, movement, heart rate, eating behaviour, and hormone secretions fluctuate in a synchronized way. This includes the neurotransmitters dopamine, histamine, norepinephrine, and serotonin. All responsible for mood and alertness.
And this evidence is also logical. We know that stress causes several physiological changes in the body and that this often results in tiredness, and a lack of focus and motivation. So, it makes sense that natural rises and falls of these same physiological chemicals and hormones would also affect alertness, energy, and focus.
Using daily ultradian rhythms to your advantage
Can we predict when we are going to be at our best for focus, energy, and mood?
Yes and no. One of the theories surrounding ultradian rhythms being less predictable than circadian rhythms is the adaption over time for survival. Being predictable is not a good trait to keep yourself out of harm’s way in an evolutionary sense. Even today, variability of behaviour can be hugely beneficial to both safety and fulfilment. Approximations can be made however. And these can maximise your potential based on knowledge of ultradian rhythms. And this is best done by being aware of your own personal patterns during the day. Now that you are aware of the idea of waves of alertness and energy., you can start to notice patterns that repeat during your day. Use the 90-120 minute timeframe as a baseline and go from there. In fact., you could try taking a short break from your current activity every 90-120 minutes. Or you can become more aware of how you feel and use body and mind cues. Productivity experts will all tell you that regular breaks will increase productivity.
How to take a break for maximum performance
Does taking a break mean you need to rest?
No. All it needs to be is both different and undemanding of body and mind. In fact, studies show that engaging in a non-demanding but slightly active activity is better for creativity than having a rest.
So, an example might be the following. If you are writing an article (as I am doing now), then an example of a break could be folding and putting away laundry or doing some dishes. If you are working in the garden, an example could be sitting down and having a drink while you listen to the sounds of nature. 10-20 minutes is a good average time for a break. Try If you can, to make your break mildly physical from a mental task, or mildly mental from a physical task. This will maximise the effect in the shortest time. Notice what length of time works for you and don’t be afraid to experiment or adjust day to day. If you’re on a roll and doing something well., keep doing it and extend the time before a break. Be aware however that the effect of not taking breaks can result in lower peaks of performance as the day goes on.
Be aware also, that unless you get your circadian rhythm synchronised to optimal living., maximising your ultradian rhythms will be unlikely to be successful.
The longest of the biological rhythms that govern our lives are infradian and circannual rhythms. Circannual rhythms are as the name suggests, cycles lasting a year. Although in practice these are usually considered an infradian rhythm. Infradian rhythms are cycles that last longer than 24 hours. Infradian rhythms influence the brain, metabolism, immune system, microbiome, stress response, and the reproductive system. The most known infradian rhythm is the menstrual cycle that most women experience every 28 days. Normal ranges can be between 21 and 35 days. Even this can be influenced by the environment. For example, timing synchronisation can occur between women who spend time together. This is believed to be because of pheromones activating hormones via smell. Several hormones are involved and are co-ordinated by the pituitary gland.
And research shows the pituitary gland can be influenced by light and melatonin levels. Perhaps an evolutionary response to longer light periods being an indication of months were food and warmth are in more abundance for offspring.
Balancing biological monthly cycles
The menstrual infradian rhythm is mainly controlled by internal endogenous pacemakers. External factors can affect the experience though. And some women have found ways to use this to their advantage and minimise discomfort. Unfortunately, external factors can affect monthly cycles in a negative way. Knowing when and what to eat, when and how much to exercise, and when to engage in specific tasks can improve many negative effects. The idea is that there are 4 phases within each of these 28-day cycles. Cycles within cycles again. And each of these phases has different levels of hormone production. Meaning that in each of these phases, you will respond to the same stimulation differently. Planning around this monthly rhythm can help maximize energy peaks and get rest when the body is ready for downtime. If you still experience challenges, your doctor may recommend diet changes, supplements and/or hormone replacement therapy.
The four phases of a woman’s monthly cycle
Here are the 4 phases (approximate lengths) and some suggested examples of how to be in tune with them.
Menstruation phase (days 1–5): Levels of hormones reduce significantly. The result of which is that levels of serotonin are also low. Therefore, mood and sleep may be harder to regulate. Depressive thoughts may be more common. Go easy on yourself and schedule in some ‘me time’. Gentle exercise like yoga may be best here. Practice good sleep habits like limiting screen time and too much light in the evenings.
Follicular phase (days 6–14): Metabolism lower meaning less energy/calories are used. Adjusting what you eat can help here. Start to gently increase exercise as energy levels improve.
Ovulatory phase (days 15–17): Hormone levels are at their highest. And so too is serotonin. In this phase it may be easier to maintain a positive mindset and focus. Energy is at its peak so exercise may be easier and more enjoyable.
Luteal phase (days 18–28): Metabolism is higher meaning you use more energy/calories. Energy may begin to reduce as you approach the end of this phase. A good time to focus on lower intensity strength building workouts. Hormone levels begin to reduce. Start to pay more attention to winding down before bed to get quality sleep.
Infradian rhythms – Seasonal Affective Disorder (SAD)
The other most common infradian rhythm is a seasonal pattern of depression caused by a lack of light. This is referred to as seasonal affective disorder (SAD) and occurs every year in some people. It occurs mainly in winter months and can often be resolved using artificial bright light. This biological rhythm has close links to the circadian rhythm and people with SAD often have challenges with sleep also. Highlighting the importance of getting light at the right times to control relaxation and arousal times. Recent findings also show that increased exposure to light triggers other responses. A few examples being a faster metabolism, faster hair and nail growth, higher levels of sex hormones, and a stronger immune system. And that it’s not just light on the skin that influences this. But light into the eyes is part of that response also. Again, potentially an evolutionary response to better months for being active. Avoiding SAD during the winter months involves many of the same principals as maintaining a healthy circadian rhythm. Exposure to light and consistent bedtimes being the main ones.
Seasonal Affective Disorder overview >>>
Circannual rhythms – combining internal clocks with seasons
Animals and birds are best known for having biological rhythms that respond to annual cycles. Generally, they combine internal timekeeping with external cues. This prepares them for predictable, annual changes in the environment. For example, hibernation and migration are adaptations to environmental conditions like temperatures and food supply. Early humans had these same habits. Both in response to the same environmental cues, and to follow the animals. Day length is the most reliable of these cues. Although temperature and other factors can also influence these yearly rhythms. Living near the equator where light changes less, promotes a higher reliance on internal cues. Is this yearly pattern still relevant to humanity today? Certainly, global climate changes are affecting these cycles. Man-made or not, the less predictable nature of seasons brings with it potential challenges. And not just for tribal peoples who live ‘with’ nature. Studies on circannual rhythms in humans are sparce. And usually, the topic of infradian rhythms includes part of what might be considered a yearly cycle. However, our patterns of eating, shifting to follow warmer climates, and even reproducing., still seem to be influenced by the time of year.
Circannual rhythms in humans
In the animal kingdom, changes in seasons also brings changes in hormone levels, and subsequent behaviour. These same changes it seems, can be measured in humans. But it’s not something that is widely talked about. Technology and distribution have removed changes in food supply, warmth, and light. However, the effects of the changing seasons are still there. Belief is maintained also by some that lunar (moon) cycles influence us. Evidence for this being a biological rhythm however is limited. Studies show that a person’s time of birth and risk of disease and death are not random across the year. Science cannot fully explain why this seasonality still exists. Possibly, these cycles are responses that evolved in our ancestors and as such have an evolutionary aspect to them. Research supports the idea that humans are a seasonal species that responds to changes in daily light over the year. Activity is influenced by daylight. And the timing of this activity differs between populations in different geolocations.
Using circannual rhythms on purpose
There’s not a lot you can do to change how you physically respond to circannual rhythms. But you can change how you respond mentally. Autumn/fall might well be a time to ponder where you are and where you want to be. And also a time to let things go ready for winter. Winter might be a time to get into good habits that will see you through any challenge that comes your way. Spring might be the time for new idea’s to be brought to life. A time for accelerated growth. And summer., maybe this is the time to celebrate it all and enjoy the fruits of your labour!?
You get to choose.
Circannual rhythms passed on to offspring
Maternal Light exposure in certain mammals has been indicated to influence the wellbeing, brain function and the endocrine system (thyroid, pituitary, adrenals) of offspring. How this translates to humans is little understood. An example of this in humans, is that patients who suffer from anorexia, are much more likely to have been born in spring and much less likely to have been born in autumn. The patterns and distribution of this and other markers of health and disease suggest a link. These are the subject of newer studies. Animal studies are much easier to conduct. And they have shown many correlations. So, it’s not too far of a stretch to think the same may apply to us.
Circannual (yearly) rhythms >>>
Biological rhythms and wellbeing summary
The overall lesson here with biological rhythms seems to be one of knowing your own body and mind. The reason some of these rhythms are hard to measure in humans, is the answer to how to use them. We are all different and no one solution is going to help everyone. There are generalisations to be made, however. Think in terms of waves of chemical balance in the body. Waves of alertness and need for rest being the main affect we notice. At any given moment you will be somewhere on that ride of peak to trough and back again. Learn what those times are for you. But start with the knowledge of what science says is normal. Listen to you body. Pushing through tiredness can work short term. But what if instead you took 10 minutes to relax or change your activity? Staying up late can be fun. But what if instead you adopt regular sleep patterns? Get in tune with your biological rhythms and notice how much more energy, motivation, and good feelings you enjoy.
Thinking and lifespan (brain hormesis) >>>>
Integration of psychedelics >>>>
Holistic light therapy and brainwave entrainment >>>>