When people colloquially refer to a man's "day," they are not referring to the weekly or monthly fluctuations that women experience. Instead, they are referring to the daily fluctuations in testosterone levels in men, which rise and fall throughout the day. The fact that male hormones also follow cycles was definitively established in 2012 as part of the Mars-500 observational study. A hormonal cycle was observed in men for the steroid hormone aldosterone (a 28-day cycle). However, the data only allowed for inferences about a 7- or 14-day cycle for the hormones testosterone and cortisol ( Rakova et al., 2013 ).
Besides natural fluctuations throughout the day, testosterone levels can also decrease or fluctuate due to age, lifestyle factors, and underlying medical conditions. These fluctuations can significantly impact men's physical and mental health. In this article, we examine the causes and effects of these fluctuations and their relevance to the diagnosis of testosterone levels, aiming to provide a more comprehensive understanding of this important hormone.
Causes of testosterone fluctuations
Testosterone fluctuations can be caused not only by the so-called "circadian rhythm" throughout the day, but also by increasing age, lifestyle factors, and co-existing medical conditions. These fluctuations can have a significant impact on men's physical and mental health.
The daily fluctuations due to the circadian rhythm
As previously mentioned, the male testosterone cycle is diurnal. Testosterone levels are typically higher in the morning and decrease throughout the day ( Brambilla et al., 2009 ). This daily pattern, known as the circadian rhythm, must also be considered when scheduling blood tests to obtain consistent and comparable results. The daily fluctuations caused by this bodily rhythm actually lead to significant differences in testosterone levels. In the evening, the same test subjects exhibit testosterone levels that are up to 12.9% lower. This fluctuation is referred to as intraindividual biological variation throughout the day. A study by Collier et al. (2010) shows that serum testosterone levels were 1.5 nmol/L (43 ng/dL) lower in the afternoon than in the morning.
The time of day is therefore a very relevant factor for testosterone levels. For this reason, testosterone levels in the blood should always be measured at the same time in the morning for better comparability.
The influence of lifestyle
Furthermore, these natural fluctuations throughout the day can be further influenced by sleep patterns, diet, and physical activity. For example, the intra-individual biological variation between different days for morning serum testosterone was as high as 18.7%, even greater than that caused solely by the time of day. This is where lifestyle factors such as chronic stress, sleep deprivation, lack of exercise, and the consumption of harmful substances like alcohol come into play ( Collier et al., 2010 ).
Stress: Stress is a significant factor that can have a lasting impact on testosterone levels. Chronic stress leads to the release of cortisol, a stress hormone that can inhibit the production and release of testosterone. Reducing stress through techniques such as meditation, yoga, or simply regular rest and relaxation can therefore have a positive effect on testosterone levels ( Xiong et al., 2021 ). Acute stress also has a direct impact on testosterone levels, with short-term increases observed alongside cortisol. It is suggested that testosterone plays an adaptive role in conjunction with cortisol during acute stress phases ( Zueger et al., 2023 ).
Sleep: Furthermore, poor sleep quality can negatively affect testosterone levels. Regular, sufficient, and high-quality sleep is essential for maintaining a healthy hormonal balance. Research shows that a lack of sleep, particularly a reduction in REM sleep phases, can lead to a significant decrease in testosterone levels ( Agrawal et al., 2022 ). It has even been shown that an acoustic noise that disrupts sleep quality can lower testosterone levels in the morning. Therefore, even one night of poor sleep can have a negative impact on testosterone levels in the short term ( Ukraintseva et al., 2018 ).
Exercise: During endurance and strength training, testosterone levels rise, and often remain elevated for some time after the workout before leveling off again. The long-term positive effects of exercise on testosterone levels are likely primarily due to weight loss ( Riachy et al., 2020 ).
Alcohol consumption: Studies have repeatedly shown that excessive alcohol consumption has a lasting negative impact on testosterone levels ( Smith et al., 2023 ). Chronic alcohol consumption is thought to inhibit the hormonal axis in healthy men. However, the precise mechanisms that explain the link between alcohol consumption and impaired steroid hormone production are not yet fully understood ( Santi et al., 2023 ).
Comorbidities
In addition to the factors already mentioned, certain comorbidities can also lead to low testosterone levels. A particularly strong correlation exists between type 2 diabetes, metabolic syndrome, and testosterone deficiency—therefore, testosterone levels should be closely monitored in these patients ( Traish et al., 2011 ). You can read more details on this topic in our expert blog post, " Why Diabetics Should Absolutely Keep an Eye on Their Testosterone Levels ."
The age-related decline in testosterone
Testosterone levels in men decline with age. This age-related decline in testosterone usually begins between the ages of 35 and 55 ( Matsumoto, 2002 ). During this lifespan, men experience a decrease in their testosterone levels of approximately 1-2% per year ( Stanworth & Jones, 2008 ).
This decline in testosterone levels is a natural part of aging, similar to menopause in women. However, this so-called "andropause" differs in that the testosterone decline is gradual and occurs over a longer period. It is not an acute fluctuation in testosterone levels, such as those associated with the circadian rhythm, but rather a long-term development. Regardless, a pronounced testosterone deficiency in old age should by no means be considered "normal." Instead, it is a pathological condition caused by an unhealthy lifestyle and related health problems. In our expert article " Myths and Facts about Testosterone, " we address this myth in detail. You can also learn more about testosterone deficiency in our article: " Testosterone Deficiency in Men: Causes, Symptoms, and Solutions ."
Symptoms of testosterone fluctuations
A balanced testosterone level is crucial for men's health. Testosterone influences numerous physical, psychological, and sexual functions. Short-term fluctuations in testosterone levels are normal in many cases, such as the body's reaction to short-term stress or exercise. However, chronic changes, such as those caused by persistent sleep problems, chronic stress, or alcohol consumption, can cause a variety of symptoms that can significantly impair well-being and quality of life. A deficiency or imbalance can thus lead to various physical, psychological, and sexual symptoms:
- Physical symptoms : The most common physical signs include muscle weakness, weight gain, and decreased bone density. Men may notice a decline in physical performance ( Wittert et al., 2003 ).
- Psychological symptoms : Fatigue, mood swings, depression, and concentration problems can also indicate low testosterone levels. These symptoms can significantly impair quality of life ( Wang et al., 2000 ).
- Sexual health : Loss of libido and erectile dysfunction are common symptoms of testosterone deficiency. These problems can negatively impact both personal well-being and intimate relationships ( Hintikka et al., 2009 ).
Relevance of fluctuations for diagnostics
Due to the complexity of hormonal regulation in the body, influenced by numerous factors such as age, time of day, and lifestyle, several things should be considered when determining testosterone levels.
Short-term fluctuations
Short-term fluctuations in testosterone levels are particularly important for determining the optimal time for sample collection. Since testosterone levels follow a circadian rhythm, as previously described, blood samples for level determination are typically taken in the early morning hours when testosterone levels are highest ( Brambilla et al., 2009 ). All subsequent tests should ideally be performed at the same time of day to ensure comparability.
Medium-term fluctuations
Medium-term fluctuations, for example due to stress or lack of sleep, can temporarily alter basal testosterone levels. A single testosterone measurement therefore only provides a snapshot that may not reflect the actual hormonal landscape. Multiple blood tests, on the other hand, offer a dynamic and comprehensive picture of hormone status and are thus crucial for a correct diagnosis and subsequent treatment planning. To diagnose hypogonadism, a second test is always necessary to confirm an abnormal initial test result ( Bassil et al., 2009 ). You can find more information on this topic in our blog post " Considering Testing Your Testosterone Levels: Why You Need Multiple Blood Tests ."
Long-term fluctuations
As previously mentioned, an unhealthy lifestyle, comorbidities, and age can all lead to chronically lower testosterone levels, potentially resulting in a manifest deficiency. This is relevant because many men are unaware that they may be suffering from testosterone deficiency, especially if it develops gradually and symptoms are interpreted as signs of aging. Therefore, it is advisable to have testosterone levels checked if symptoms suggest a deficiency, in order to rule out a deficiency or treat it if necessary ( Traish et al., 2011 ).
Our conclusion, your knowledge
Fluctuations in testosterone levels can be caused by various factors such as circadian rhythms, age, lifestyle, and co-existing medical conditions. These fluctuations have far-reaching effects on physical, mental, and sexual health. Precise diagnostics are crucial to identify the cause of symptoms and take appropriate action. Testosterone level measurements should always be performed taking into account natural fluctuations and individual differences. Multiple blood tests, ideally at the same time of day, are necessary to obtain a comprehensive picture of hormonal status and to make an informed diagnosis.
In conclusion, understanding the fluctuations in testosterone levels is a crucial foundation for promoting men's health. Through awareness and early diagnosis, men can take proactive steps to support their hormonal balance and sustainably improve their well-being. With these insights, we hope to have given you a better understanding of the significance of testosterone levels and their impact on your health. Use this knowledge to actively manage your health and seek professional support when needed.
