CAN TIME OF DAY AFFECT TESTOSTERONE LEVELS?

Testosterone is a hormone that naturally rises and falls throughout the day. For most people, levels are highest in the morning and gradually decline by evening. These changes follow a pattern called a circadian rhythm, which is influenced by sleep, light exposure, and daily activity.

For younger adults, the difference between morning and evening readings can be significant, sometimes up to 30%. As people age, this daily variation becomes smaller, meaning the timing of a test becomes slightly less critical. However, for accurate diagnosis or monitoring, it’s still important to understand when testosterone peaks and when it naturally drops.

At One Day Tests, we help you choose the right time for your test to ensure accurate, laboratory reviewed results. Whether you book a clinic appointment or take your test at home, our guidance follows UK endocrine best practices to make sure your results truly reflect your hormone levels.

To check your hormone balance accurately, book a  testosterone blood test with One Day Tests, with fast, lab-reviewed results that show how your testosterone levels vary throughout the day.

Testosterone production follows a daily cycle that is closely tied to your sleep and wake pattern. Levels usually:

• Peak early in the morning, typically between 7 am and 11 am.
  
  

• Gradually fall through the afternoon.
  
  

• Reach their lowest point in the evening and overnight.
  
  

This rhythm is most noticeable in men under 45, where morning levels can be up to one-third higher than those measured in the afternoon. In older adults, the daily rise and fall becomes less pronounced because the body’s natural hormone rhythm flattens over time.

Disrupted sleep, shift work, or irregular routines can also affect this pattern. People who work night shifts, for example, may experience their “morning” testosterone peak at a different time of day, depending on their sleep schedule.

These natural changes mean that the time of your test can make a real difference in how your results are interpreted. At One Day Tests, we typically recommend morning testing, between 7 am and 11 am, to capture peak hormone levels and ensure consistency with NHS and endocrinology guidelines.

Testosterone levels are not constant, so the timing of a blood test has a direct impact on the accuracy of your result. Because testosterone peaks early in the morning and falls as the day progresses, testing later in the day may underestimate your true hormone levels.

For younger adults, this difference can be quite significant, morning levels can be 25–30% higher than evening readings. This means that if a test is taken after midday, it could suggest low testosterone when levels are actually normal for that person’s age and daily rhythm.

For men over 45, the variation throughout the day is smaller, and testing up to around 2 pm is still considered accurate. This is because the circadian rhythm that controls testosterone release becomes flatter with age. Still, consistency is important. Testing at the same time each day helps ensure that comparisons between results remain reliable, especially if you are monitoring changes or treatment response.

Doctors also consider factors such as sleep, illness, and recent exercise when interpreting testosterone results. A single reading taken at the wrong time or after poor sleep may not reflect your usual hormone levels. If your test result is borderline or unexpectedly low, your clinician may recommend repeating the test on a different morning to confirm it.

At One Day Tests, we follow best practice guidelines by recommending that testosterone tests are taken between 8 am and 9 am. Our tests are processed in our accredited UK laboratory, and every result is reviewed by our laboratory before you get the results. Our GPs can advise you on next steps if retesting or further investigation is needed.

Testosterone levels can fluctuate for reasons beyond time of day. Several short-term and long-term factors can affect hormone balance, including:

• Sleep: Poor or disrupted sleep reduces testosterone production and can flatten the natural daily rhythm.
  
  

• Stress: Chronic stress increases cortisol, which can lower testosterone over time.
  
  

• Diet: Low-calorie diets, nutrient deficiencies, or excessive alcohol use can affect hormone balance.
  
  

• Exercise: Regular strength training can boost testosterone, while overtraining may temporarily reduce it.
  
  

• Medications: Steroids, opioids, and some antidepressants can interfere with hormone production.
  
  

• Illness: Acute or chronic illness, including obesity and type 2 diabetes, can suppress testosterone levels.
  
  

These factors often overlap. For example, someone working irregular hours might have disrupted sleep, higher stress levels, and altered eating habits, all of which can influence hormone levels. Tracking testosterone alongside lifestyle habits provides valuable context for interpreting your results.

At One Day Tests, our hormone panels allow you to retest and monitor your levels over time. This helps identify whether low results are temporary or part of a longer-term trend that may require medical attention.

Low testosterone can cause a range of physical and emotional symptoms. These can develop gradually, making them easy to overlook. Common signs include:

• Fatigue and low energy
  
  

• Reduced muscle strength or slower recovery after exercise
  
  

• Decreased libido or sexual performance changes
  
  

• Mood changes, including irritability or low mood
  
  

• Poor concentration or difficulty sleeping
  
  

• Increased body fat or loss of muscle mass
  
  

Because testosterone affects multiple systems in the body, symptoms can vary widely between individuals. If you notice ongoing fatigue, changes in mood, or reduced physical performance, a blood test can help identify whether your hormone levels are contributing.

At One Day Tests, you can check your testosterone levels quickly and easily through home or clinic testing. All results are laboratory-reviewed, with clear guidance on what they mean and whether further investigation or treatment is recommended.