While sleep is a time for the body to rest and recover, certain nighttime symptoms can be early indicators of serious health conditions — including cancer. Paying attention to unusual changes during sleep could help with early detection and improve treatment outcomes. Here are three symptoms that may serve as red flags:

1. Night Sweats

Occasional sweating at night may result from a warm room or thick blankets, but persistent, drenching night sweats — even in a cool environment — could indicate a more serious issue. Certain cancers such as lymphoma, leukemia, and some hormone-related tumors can trigger the body to produce excess sweat during sleep.

2. Unexplained Weight Loss While Sleeping

If you’re losing weight without changing your diet or activity levels — especially if it seems to happen overnight — it could be a sign that your metabolism is being affected by cancer. Tumors often increase the body’s energy consumption or alter hormone levels, leading to unintentional weight loss.

3. Persistent Coughing or Difficulty Breathing at Night

A lingering cough or shortness of breath that worsens at night might be more than just a respiratory issue. Lung cancer or cancers that spread to the lungs can cause these symptoms, particularly when lying down. If you often wake up coughing or gasping for air, it’s worth getting checked by a doctor.