Late-night salivary cortisol is a noninvasive test measuring cortisol in a saliva sample collected late at night (usually around 11 PM) to assess the normal overnight fall in cortisol. It screens for Cushing’s syndrome or disrupted diurnal rhythm: elevated late-night levels suggest loss of normal suppression. Collection is convenient, at-home, and relatively resistant to brief stress; abnormal results often need confirmatory testing.

The best time for a saliva cortisol test is immediately on waking and 30 minutes later to measure the cortisol awakening response, plus a late-night or bedtime sample to assess the daily nadir. Collect samples on a typical day, avoid eating, drinking, smoking, brushing teeth or strenuous exercise before collection, and follow exact timing instructions for accurate results.

Late-night salivary cortisol measures free cortisol in a saliva sample collected around 11 pm to assess loss of the normal diurnal cortisol nadir. It’s a convenient, noninvasive first-line screen for Cushing’s syndrome: elevated late-night levels (confirmed on repeat sampling) suggest endogenous cortisol excess and disrupted circadian rhythm. Proper collection timing and avoiding topical/systemic steroids are essential for accurate results.

A late-night salivary cortisol test measures cortisol in a saliva sample collected late at night (usually around 11 p.m.) to assess the normal evening drop in cortisol. It’s a noninvasive screening tool for Cushing’s syndrome or abnormal cortisol rhythms. Elevated late-night levels suggest hypercortisolism. Samples are self-collected with strict timing and preparation rules (avoid food, smoking, some meds, and contamination).

At your usual bedtime, avoid eating, drinking, smoking, brushing teeth, chewing gum, or vigorous exercise for at least 30 minutes. Rinse your mouth with water and wait 10 minutes. Collect saliva using the provided swab or Salivette—place it under the tongue for 1–2 minutes until saturated. Seal and label with date/time, refrigerate or freeze per instructions, and return the sample promptly. Note medications or illness.

Cortisol can be high at 3 a.m. because of your circadian rhythm—cortisol normally falls overnight and begins rising before waking. Early or exaggerated rises occur with chronic stress, poor or fragmented sleep, nighttime awakenings, shift work or early schedules. Medical causes include sleep apnea, steroid medications, Cushing’s syndrome or acute illness. If persistent or symptomatic, get medical evaluation and consider sleep and stress-management strategies.