Body Signals Adults Often Dismiss but Probably Shouldn't

Feeling tired after a poor night's sleep is expected. But fatigue that lingers for weeks despite adequate rest — and that interferes with daily function — is a different matter. Clinically significant fatigue can be associated with conditions ranging from anemia and thyroid dysfunction to sleep-disordered breathing and depression. Because adults tend to normalize exhaustion as a byproduct of busy lives, this signal often goes unevaluated for months. If fatigue is your baseline rather than the exception, it warrants a conversation with your doctor. Learn more about one common culprit in our explainer on sleep apnoea.

Weight fluctuates day to day for many reasons. However, unintentional weight loss or gain of 5% or more of body weight over six to twelve months — without a clear dietary or activity explanation — is generally considered clinically significant. Unintentional weight loss in particular is associated with a wide range of conditions, including thyroid disorders, gastrointestinal disease, and malignancy. Unexplained gain may reflect hormonal changes, medication effects, or metabolic shifts. Neither should be automatically attributed to age or habit without assessment.

Occasional heartburn after a heavy meal is common. Frequent, recurring indigestion — especially if it has changed in character, wakes you at night, or is accompanied by difficulty swallowing — is worth investigating. Chronic acid reflux (GERD) can, over time, cause changes to the esophageal lining. Indigestion that develops for the first time in midlife or later, or that doesn't respond to typical measures, may also occasionally reflect cardiovascular or upper gastrointestinal issues. Our digestive symptoms reference guide outlines which patterns generally warrant prompt attention.

Thirst is the body's normal signal to rehydrate. But thirst that feels constant, is disproportionate to your activity level or fluid intake, and is accompanied by frequent urination can be an early indicator of conditions such as type 2 diabetes or diabetes insipidus. Because these conditions can be asymptomatic for extended periods, polydipsia (persistent excessive thirst) is sometimes one of the first noticeable signals. A straightforward blood or urine test can typically rule in or out several relevant causes.

Some breathlessness during intense exercise is normal. Becoming noticeably winded while climbing one flight of stairs, walking at a moderate pace, or doing light housework is not. Adults often attribute this to being out of shape and delay seeking evaluation. However, exertional breathlessness can reflect cardiovascular, pulmonary, or metabolic conditions — some of which benefit considerably from early detection. For a detailed look at when breathlessness crosses into territory worth investigating, see our article on shortness of breath.

Most headaches are benign, but headaches that are new in adulthood, progressively worsen, occur with increasing frequency, or are accompanied by neurological symptoms — such as visual changes, confusion, or weakness — are a different category. So is a headache described as the worst of one's life, which can be a red flag for serious vascular events. Headache patterns also shift across life stages, making it useful to understand the distinction between routine and concerning headaches.

A single episode of constipation or loose stools usually isn't cause for concern. Persistent changes — such as new-onset constipation, unexplained diarrhea, pencil-thin stools, or alternating patterns lasting several weeks — are worth discussing with a clinician, particularly in adults over 45. These can sometimes reflect inflammatory bowel conditions, irritable bowel syndrome, or, less commonly, colorectal changes that benefit from early screening. Rectal bleeding or black, tarry stools should never be ignored and warrant prompt evaluation.