A bidirectional relationship between obesity and low testosterone underpins this association, as indicated by the hypogonadal-obesity cycle and weight loss leading to increased testosterone levels (Fig. 1). Obesity is strongly linked to low testosterone levels in men, as is increased fat mass, especially abdominal fat. The increase in testosterone at the time of sleep, the decrease during the time of awakening, is stable within an individual, although there is large variability among individuals . Serum testosterone levels vary in a circadian manner, being higher during waking hours and the decreasing to a low level at the end of the day . These two categories of sleep have a 90 minutes cycle, and normal adults repeat this cycle four to six times during the night. NREM sleep accounts for 75% to 80% of total sleep time, and REM sleep accounts for the remaining 20% to 25% . More severe obstruction of the upper airway during sleep results in the obstructive sleep apnea (OSA) or OSA syndrome (OSAS) when there are compatible symptoms present. In some people, though, testosterone replacement therapy can interfere with sleep, especially if it is a high-dose treatment. When low testosterone causes poor sleep, testosterone treatment may improve sleep. At the same time, poor sleep may interfere with normal testosterone production. When testosterone levels are too high or too low, it may impact sleep. Sleep position is among the most impactful — sleeping on your back allows gravity to pull the tongue and soft tissues backward, narrowing the airway. Beyond devices and medical interventions, several lifestyle modifications can meaningfully reduce snoring testosterone. The Snorple mouthpiece was specifically engineered around this combined approach, based on clinical evidence that dual-mechanism treatment produces significantly better airway opening than either approach alone. Mandibular advancement devices (MADs) work by repositioning the lower jaw slightly forward during sleep, which increases the space behind the tongue and reduces the likelihood of airway collapse. By the time symptoms become impossible to ignore, the underlying damage may be significant. What makes low testosterone sleep particularly dangerous is how gradually the damage accumulates. These are not hypothetical risks — they are documented outcomes of prolonged oxygen deprivation during sleep. Furthermore, the severity of hypoxia during sleep, as indexed by the ODI and O2 nadir, is strongly correlated with the reduction in testosterone . Several studies have confirmed a strong relationship between OSA and low testosterone. The first REM sleep appears 80 to 100 minutes after the start of sleep, and the time between the first REM sleep and sleep onset is termed the REM latency 10,11. Serum testosterone has been shown to be lower in men with OSA and treatment of OSA may help improve hypogonadism and sexual function 7,8,9. However, because TRT may exacerbate OSA in some patients, patients should be asked about OSA symptoms before and after starting TRT. Obstructive sleep apnea (OSA) is a common disorder characterized by intermittent hypoxia and sleep fragmentation. Millions of American men use a prescription testosterone injection or gel as forms of testosterone replacement therapy (often referred to as TRT therapy) to restore normal levels of the manly hormone. If low-T is the culprit behind your sleep issues, our team can make that diagnosis and restore your testosterone levels and production. Your body needs to achieve the sleep stage called rapid eye movement (REM) to replenish the testosterone and other hormones you use during the day. All this commotion interferes with your sleep quality, so even if you think you sleep through the night, your body doesn’t get the restorative rest it needs. Here, our hormone specialists at The Endocrine Center in Houston, Texas, explain the two-way relationship between low testosterone and sleep apnea. Many factors can disrupt your testosterone level, but one of the lesser-known culprits is sleep quality — so if you have sleep apnea, there may be a connection.