Night Sweats in Men: What's Actually Causing Them

Night sweats get discussed almost exclusively in the context of menopause. This leaves men who wake up sweating without useful information and often without an explanation. Night sweats in men are common across all adult age groups, and the causes are specific, identifiable, and in most cases addressable. The problem is that nobody talks about them in male-specific terms.

Low Testosterone

Testosterone plays a direct role in hypothalamic thermoregulation. The hypothalamus, the brain region that acts as the body's thermostat, has testosterone receptors. When testosterone falls below optimal levels, the hypothalamus becomes less stable in its temperature regulation, and the threshold at which it triggers sweating drops. The result is the same mechanism that produces hot flashes and night sweats in menopause, just driven by a different hormone deficiency.

Low testosterone affects roughly 38 percent of men over 45, and the prevalence increases with age. But low testosterone is not exclusively a condition of older men. Younger men who are chronically sleep-deprived, significantly overweight, or under sustained stress can develop clinically low testosterone because the same physiological conditions that produce poor sleep also suppress testosterone production.

The sleep-testosterone cycle is self-reinforcing in the wrong direction. The majority of daily testosterone is produced during sleep, particularly during slow-wave and REM sleep. Night sweats that fragment sleep reduce the time spent in these stages, which reduces testosterone production, which worsens the thermoregulatory instability, which causes more night sweats. Breaking this cycle typically requires addressing both the sleep quality and the testosterone levels simultaneously.

Sleep Apnea

Sleep apnea is one of the most underdiagnosed causes of night sweats in men, and the connection is almost never made in general health content.

During an obstructive sleep apnea event, the airway collapses and breathing stops. Oxygen in the blood drops, carbon dioxide rises, and the brain detects an emergency. It triggers an arousal response to restart breathing, which involves a burst of adrenaline and cortisol. This hormonal surge raises heart rate, blood pressure, and body temperature. Sweating follows.

Men with untreated sleep apnea can have dozens or hundreds of these events per night, each producing a small adrenaline surge. The cumulative thermal load from these repeated surges is enough to cause significant sweating even without full waking. Many men with sleep apnea wake only occasionally but sweat consistently, which they attribute to other causes because they do not connect it to apnea events they are not consciously experiencing.

Sleep apnea affects approximately 25 percent of men, compared to around 9 percent of women. Obesity, large neck circumference, alcohol use, and sleeping on the back all increase risk. If night sweats come with loud snoring, witnessed apneas by a partner, morning headaches, or daytime sleepiness, a sleep study is worth pursuing. Treating sleep apnea resolves the night sweats in most cases.

Alcohol

Alcohol is the most preventable cause of night sweats in men and one of the most consistently overlooked.

Alcohol causes vasodilation, which opens blood vessels near the skin and allows heat to dissipate from the surface of the body. Core body temperature initially drops. As the liver metabolises alcohol and blood alcohol levels fall, the body reverses this process. Blood vessels constrict, core temperature rebounds, and the thermoregulatory system overcorrects, generating sweating to release the excess heat.

This rebound typically occurs in the second half of the night, two to six hours after the last drink, which is why men often sleep reasonably well initially but wake sweating in the early hours after evening drinking.

Alcohol also disrupts blood glucose regulation overnight by impairing the liver's gluconeogenesis, the process by which the liver maintains blood glucose during fasting. Blood glucose drops during the night, the body releases adrenaline and cortisol as a counter-regulatory response, and sweating follows. This pathway compounds the direct thermal effect.

Anxiety and Stress

The relationship between anxiety, cortisol, and night sweats applies equally to men. Chronic stress keeps cortisol elevated through the night, and cortisol raises core body temperature. The 3 to 4am cortisol uptick that occurs naturally is amplified in people under sustained stress, producing sharp waking with sweating and a feeling of alertness in the early hours.

Men are statistically less likely to identify or report anxiety, which means this cause is frequently misattributed to something else. If night sweats are concentrated in the second half of the night and accompanied by a mind that will not quiet, cortisol dysregulation is likely involved.

Hyperthyroidism

An overactive thyroid produces excess thyroid hormone, which accelerates metabolism and raises baseline body temperature. The thermoregulatory system responds by sweating more readily at lower temperature thresholds. Hyperthyroidism also produces anxiety, rapid heart rate, and weight loss despite normal or increased appetite.

Thyroid disorders are more common in women but affect men too, and they are frequently missed in men because thyroid problems are not routinely screened for in male health contexts. A simple blood test measuring TSH and free T4 confirms or rules this out.

The Sleep-Testosterone Cycle

The connection between sleep quality and testosterone is worth emphasising because it creates a practical entry point.

Testosterone production peaks during slow-wave sleep, the deepest sleep stages that occur predominantly in the first half of the night. A 2011 study published in JAMA found that just one week of sleep restriction to five hours per night reduced daytime testosterone levels in young men by 10 to 15 percent. This is a significant drop achieved in a very short time.

Night sweats that fragment slow-wave sleep reduce testosterone production. Lower testosterone then worsens thermoregulatory stability, making more sweating more likely. The practical implication is that improving sleep quality, through any means that reduces fragmentation and supports slow-wave sleep, directly supports testosterone levels. Magnesium bisglycinate has specific evidence for improving slow-wave sleep duration, making it relevant to this cycle. For more on the evidence, see our article on magnesium for sleep.

Glycine also supports slow-wave sleep through its role in lowering core body temperature at sleep onset, which creates the thermal conditions that favour deep sleep. The research from Nagoya University on glycine supplementation consistently shows improvements in slow-wave sleep stages.

What to Do

If sleep apnea is suspected, a sleep study is the first step. Most current home sleep tests are accurate enough to confirm obstructive sleep apnea without a lab visit.

If alcohol is a regular evening habit, a two-week trial without it is the fastest way to determine how much it is contributing. Night sweats from alcohol typically resolve within a few days of stopping.

If stress and anxiety are high, addressing the cortisol pathway directly makes sense. Magnesium bisglycinate, lemon balm, and apigenin all support nervous system regulation through mechanisms with reasonable clinical evidence. The cooling effect of glycine before bed counterbalances the temperature-raising effect of elevated cortisol.

If low testosterone is suspected based on symptoms including fatigue, reduced libido, mood changes, and difficulty building muscle as well as night sweats, a testosterone blood test through a GP is the appropriate starting point.

What This Means for Your Sleep

Night sweats in men have specific causes that are identifiable and addressable. They are not a vague symptom without explanation. Sleep apnea, alcohol, low testosterone, anxiety, and thyroid dysfunction cover the majority of cases. Understanding which one applies determines what to do. For the full overview of night sweat causes and mechanisms, see our article on why you wake up sweating.