Night sweats in men have a wide range of causes, from something as simple as a warm bedroom to conditions that need medical attention like low testosterone, sleep apnea, or infections. True night sweats are episodes of sweating intense enough to soak through your sheets or sleepwear, not just feeling a little warm. If you’re regularly waking up drenched, something is disrupting your body’s temperature control system during sleep.
Your body naturally shifts its sweating thresholds as you cycle through different stages of sleep. During deep sleep, the temperature at which sweating kicks in drops lower, meaning your body starts sweating more easily. During REM sleep (when most dreaming happens), your sweat response becomes less efficient overall. These normal shifts explain why everyone sweats a little at night, but persistent, soaking sweats point to something else going on.
Low Testosterone and Hormonal Shifts
Testosterone levels in men decline by roughly 1% per year after age 40. Despite that gradual drop, most men maintain levels within the normal range and never experience night sweats as a result. The connection between testosterone and night sweats is real, but it typically only becomes a problem when levels fall sharply rather than slowly.
The clearest example comes from men receiving hormone-blocking therapy for prostate cancer. Between 70% and 80% of men on androgen deprivation therapy experience hot flashes and night sweats. Scientists know low testosterone is the trigger, though the exact mechanism linking reduced sex hormones to the sweating response isn’t fully understood. For the average man noticing night sweats in his 40s or 50s, a gradual age-related testosterone decline is an unlikely explanation on its own, but it’s worth checking if sweats are accompanied by fatigue, reduced sex drive, or mood changes.
Sleep Apnea
About 30% of people with obstructive sleep apnea report night sweats. Sleep apnea causes repeated pauses in breathing throughout the night, which drops your blood oxygen levels. Each time your body jolts awake to resume breathing, it triggers a surge in your sympathetic nervous system, the same fight-or-flight response that makes you sweat during stress. These frequent awakenings and the accompanying physical movements ramp up that stress response over and over, producing noticeable sweating by morning.
If your night sweats come alongside loud snoring, gasping during sleep, or daytime exhaustion despite a full night’s rest, sleep apnea is a strong possibility. It’s one of the more common and treatable causes. Many men find their night sweats resolve completely once the apnea is treated.
Medications, Especially Antidepressants
Several common medications can cause night sweats, but antidepressants are among the most frequent culprits. SSRIs and SNRIs, the two most widely prescribed classes of antidepressants, cause excessive sweating in 7% to 19% of patients. This includes popular medications like sertraline (Zoloft), fluoxetine (Prozac), paroxetine (Paxil), venlafaxine (Effexor), and duloxetine (Cymbalta).
Thyroid hormone replacement medication is another known trigger. If you started a new medication in the weeks before your night sweats began, or if your dose was recently adjusted, that’s a connection worth exploring with whoever prescribed it. Other drug categories linked to night sweats include blood pressure medications, blood sugar-lowering drugs, and over-the-counter pain relievers like aspirin or acetaminophen when taken regularly.
Alcohol Use and Withdrawal
Alcohol affects your circulatory system by increasing heart rate and widening blood vessels in the skin, both of which trigger sweating. Drinking in the evening can easily produce night sweats a few hours later as your body processes the alcohol. If you’re regularly waking up sweaty after drinking, it’s a straightforward cause-and-effect relationship.
Alcohol withdrawal is a separate and more serious trigger. If you’re a regular drinker and experience night sweats on nights you don’t drink, that clammy, sweaty sleep may be a withdrawal symptom. In its most severe form, alcohol withdrawal can progress to delirium tremens, which involves intense sweating, fever, hallucinations, and seizures. Frequent night sweats tied to your drinking pattern, whether from the alcohol itself or from going without it, are a sign your body has developed a significant dependence.
Infections
Night sweats are a hallmark symptom of several infections, some common and some serious. Tuberculosis is the classic association, with drenching night sweats being one of its defining symptoms alongside a persistent cough, weight loss, and fever. HIV/AIDS also commonly causes night sweats, particularly in later stages or when the virus isn’t well controlled.
Other infections linked to night sweats include endocarditis (an infection of the heart’s inner lining), brucellosis (a bacterial infection typically from contaminated food or animal contact), bone infections, and fungal infections like valley fever. With infectious causes, night sweats almost always appear alongside other symptoms: fever, unexplained weight loss, fatigue, or pain. Isolated night sweats without any other symptoms are less likely to be caused by an infection.
Thyroid and Adrenal Gland Problems
An overactive thyroid gland speeds up your metabolism, which raises your body temperature and causes generalized sweating that extends into the night. Other signs that point toward a thyroid problem include anxiety, a rapid heartbeat, trembling hands, diarrhea, sensitivity to heat, and unexplained weight loss. If you’re experiencing several of these together, a simple blood test can check your thyroid function.
A less common but more dramatic cause involves a tumor on one of the adrenal glands called a pheochromocytoma. These tumors release surges of stress hormones that produce episodes of intense sweating, headaches, rapid heartbeat, and wildly fluctuating blood pressure. A distinguishing feature: during a sweating episode caused by this kind of tumor, your hands and feet will feel cold and look pale because the stress hormones constrict blood vessels in your extremities even as you’re drenching your sheets.
Lymphoma and Other Cancers
Night sweats are one of the “B symptoms” of lymphoma, a group of blood cancers affecting the lymphatic system. In this context, the sweats tend to be severe enough to require changing your sheets or clothes, and they recur regularly. They’re typically accompanied by unexplained weight loss (more than 10% of body weight over six months) and recurrent fevers.
Cancer-related night sweats are far less common than the other causes on this list, but they’re the reason persistent, unexplained night sweats deserve attention. If your sweats are drenching, have lasted more than a few weeks, and come with weight loss, swollen lymph nodes, or fevers with no obvious source, those are patterns worth investigating promptly.
Sorting Out the Cause
The most useful first step is looking at what else is happening alongside the sweats. Night sweats with snoring and daytime fatigue point toward sleep apnea. Sweats that started after a new medication suggest a drug side effect. Sweats with anxiety, weight loss, and a racing pulse suggest thyroid overactivity. Sweats tied to drinking nights or non-drinking nights point to alcohol as the trigger.
Isolated night sweats with no other symptoms are common and often come down to a room that’s too warm, heavy bedding, or alcohol consumption. Persistent night sweats that have lasted weeks, especially with additional symptoms like unexplained weight loss, fevers, or swollen glands, call for blood work and a more thorough evaluation. A doctor will typically start with basic labs covering thyroid function, blood counts, inflammatory markers, and hormone levels to narrow the field quickly.