Shift work is a regular part of the working life for many men. Whether in healthcare, industry, the police, or emergency services, millions of men regularly work nights, early mornings, or in rotating shift systems. What is often underestimated is the significant impact of this type of work on hormone levels and thus on men's overall health.
Many shift workers report fatigue, sleep disturbances, loss of libido, weight gain, concentration problems, or mood swings. These symptoms are often caused by hormonal dysregulation, particularly low testosterone levels.
The following article explains how shift work affects hormone levels, the underlying mechanisms, and what men should be aware of. If you want to gain clarity about your hormone levels, a A targeted laboratory test is the sensible first step. Based on objective blood values, it can be assessed whether a hormonal dysregulation is present and whether a subsequent consultation with a doctor is advisable.
What is meant by shift work?
Shift work refers to working hours outside the traditional daily rhythm of approximately 7 a.m. to 6 p.m. This includes early shifts, late shifts, night shifts, as well as rotating or alternating shift systems. Night work and frequently changing shift patterns are particularly taxing on the body, as they can permanently disrupt the natural biological rhythm.
The human organism is evolutionarily designed for a clear day-night cycle ( Duffy & Czeisler, 2009 ). Many physiological processes follow this so-called circadian rhythm , including sleep-wake regulation, body temperature, metabolism, and hormone release ( Reddy et al., 2023 ).
The circadian rhythm and its hormonal significance
The circadian rhythm is centrally controlled in the hypothalamus, more precisely in the suprachiasmatic nucleus ( Reddy et al., 2023 ), a small, highly specialized region in the brain located directly above the optic chiasm. Due to this anatomical proximity, the suprachiasmatic nucleus receives direct light information from the retina and can thus act as a central timekeeper, aligning the body's internal biological rhythm with the day/night cycle and regulating the release of hormones such as melatonin and cortisol.
These hormones, in turn, influence other hormonal axes, particularly the hypothalamic-pituitary-gonadal (HPG) axis, which is responsible for testosterone production. If this rhythm is permanently disrupted, it can lead to dysregulation of several hormonal systems ( Czeisler et al., 1999 ).
How shift work affects testosterone levels
Testosterone is primarily produced at night and in the early morning hours. The highest levels in healthy men are usually found in the morning ( Brambilla et al., 2008 ). However, this requires sufficient and good-quality sleep.
Shift work often leads to shortened sleep, fragmented sleep, and a shift in sleep phases. Studies show that even a few nights of sleep deprivation can significantly lower testosterone levels ( Leproult, 2011 ). With chronic shift work, this effect can become permanent.
Additionally, night work often leads to increased cortisol release. Cortisol acts antagonistically to testosterone and can further weaken its effects at the cellular level. This shifts the balance between anabolic and catabolic hormones unfavorably ( Touitou et al., 1990 ).
Melatonin, sleep and hormonal regulation
Melatonin plays a central role in sleep quality and circadian stability. It is normally released in darkness and signals the body that it is nighttime. Artificial light at night, especially blue light, significantly suppresses melatonin release ( West et al., 2010 ).
In shift workers, nighttime melatonin secretion is often reduced or shifted in timing. This not only impairs sleep but also indirectly affects testosterone synthesis, as melatonin is linked to the regulation of gonadal function ( Luboshitzky et al., 2002 ).
Further hormonal changes due to shift work
In addition to testosterone, other hormones are often affected:
Cortisol
Shift work often disrupts the normal daily cortisol pattern. Instead of a morning peak and evening drop, cortisol remains elevated ( Weibel et al., 1996 ). Chronically elevated cortisol levels promote muscle loss, fat gain, and insulin resistance ( Abraham et al., 2013 ).
insulin
Shift work increases the risk of insulin resistance and type 2 diabetes. Impaired glucose tolerance, in turn, negatively affects testosterone levels, as hyperinsulinemia can lower SHBG levels and disrupt hormonal balance ( Gan et al., 2014 ).
Leptin and ghrelin
Sleep deprivation alters the regulation of hunger and satiety. Leptin levels decrease, while ghrelin levels increase ( Gresser et al., 2025 ). This promotes weight gain and visceral fat accumulation, which in turn encourages the conversion of testosterone to estrogen via aromatase ( Spiegel et al., 2004 ).
Typical symptoms of hormonal dysregulation due to shift work
Many symptoms develop gradually and are not initially associated with hormonal imbalances. Common complaints include:
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chronic fatigue despite sufficient sleep duration
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Loss of libido and erectile dysfunction ( Rodriguez et al., 2020 )
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reduced performance and strength
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Increase in abdominal fat ( Potter et al., 2016 )
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Mood swings and irritability ( Zheng et al., 2024 )
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Concentration and memory problems
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reduced stress resistance
Not every shift worker automatically develops a testosterone deficiency. However, the risk increases with the duration of shift work, the number of night shifts, and individual susceptibility to stress ( Viramgami et al., 2025 ).
Diagnostics for shift workers
Men who work shifts and experience related symptoms should undergo targeted hormonal testing. The timing of the blood draw is crucial. Ideally, it should be taken after a period of stable sleep and not immediately after a night shift.
Relevant parameters include, among others:
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Total testosterone
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free testosterone
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SHBG
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LH
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albumin
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Cortisol
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Melatonin may be used in special cases
The interpretation of the values should always be done in a clinical context and not considered in isolation.
When is the right time for shift workers to have their blood drawn?
For men with a regular day/night rhythm, blood sampling for testosterone is usually recommended in the morning between 8 and 11 am , as this is when the highest levels are measured.
However, for shift workers, this point in time is often not meaningful, especially after night or rotating shifts.
-> Therefore, the following applies to shift workers:
Blood samples should not be taken at a specific time of day, but rather according to the individual's sleep-wake cycle . Ideally, blood should be drawn after at least 7 to 8 hours of uninterrupted sleep, and preferably within one to three hours of waking up , regardless of whether this is in the morning, afternoon, or evening.
Therapy and prevention approaches
Not every hormonal change requires immediate medication. Often, lifestyle and work-related adjustments are the first priority.
Possible measures include:
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Optimizing sleep hygiene even in daylight
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Consistent darkness in the bedroom
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Reducing blue light before bed
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structured mealtimes
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targeted strength training
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Stress management
Testosterone therapy may be beneficial in cases of confirmed hypogonadal syndrome. However, this decision should always be made on an individual basis and under medical supervision.
You can find more information about testosterone therapy in our article " Testosterone replacement therapy: Everything you need to know ".
Shift work and long-term men's health
Long-term shift work is not only associated with hormonal changes, but also with an increased risk of cardiovascular disease, metabolic syndrome, and psychological stress ( Xi et al., 2025 ). Early awareness and regular medical check-ups are therefore essential.
Men who work shifts for years or decades especially benefit from proactively addressing their hormonal and metabolic state ( Bayon et al., 2022 ).
Our conclusion, your knowledge
Shift work places a significant strain on the male hormonal balance. Disruptions to the circadian rhythm can throw testosterone, cortisol, and other hormones out of balance. This often results in nonspecific but everyday symptoms that can significantly impair quality of life.
Targeted diagnostics, conscious management of sleep and stress, and individualized medical support are crucial to avoid long-term health consequences. Those who take symptoms seriously and act early can maintain hormonal stability and performance even while working shifts.
