His BP, cholesterol and blood sugar were normal: Yet a silent sleep disorder caused a heart attack

This repeated oxygen deprivation places a significant burden on the cardiovascular system. Oxygen levels can drop sharply during the night, a condition known as nocturnal hypoxemia, even when daytime readings are normal. The heart responds to these episodes with surges in stress hormones, spikes in blood pressure and irregular heart rhythms. Over time, this constant strain damages blood vessels and increases the risk of hypertension, stroke and heart attack. Sleep apnea is now recognised as an independent risk factor, meaning it can harm the heart regardless of other health parameters.

About 25 per cent people snore, three to four per cent of whom have sleep apnea

Snoring is widespread and often trivialised. Roughly a quarter of adults snore, but only three to four per cent report sleep apnea. The distinction is critical. While not all snorers have OSA, habitual loud snoring, especially when accompanied by choking sounds, pauses in breathing or restless sleep, should not be ignored. It may be the only visible sign of a serious underlying condition.

Why heart attack risk goes up while sleeping

Sleep is meant to be a restorative phase, but in untreated sleep apnea, it becomes a period of repeated physiological stress. Each apnea episode triggers a drop in oxygen levels followed by a sudden arousal response. This leads to abrupt increases in blood pressure and heart rate, placing acute strain on the cardiovascular system.

Untreated OSA can double the risk of heart attacks and significantly increase the likelihood of fatal cardiac events during sleep. The heart is repeatedly stressed at night, when it should be recovering. Arrhythmias or irregular heartbeats are more likely, and the combination of oxygen deprivation and pressure surges can precipitate a cardiac event without warning.

What causes sleep apnea

The causes are often a combination of anatomical and lifestyle factors. Excess weight is a leading contributor, as fat deposits around the neck narrow the airway. Structural features such as a thick neck, small jaw or enlarged tonsils can also predispose individuals. Alcohol consumption, smoking and sedative use relax the airway muscles further, increasing the likelihood of collapse during sleep. Age and gender play a role, with higher prevalence in middle-aged men, though risk rises in women after menopause.

How to prevent heart attacks from sleep apnea

Prevention begins with recognition. Addressing sleep apnea early can significantly reduce cardiovascular risk. Weight loss remains one of the most effective strategies; even a reduction of 10 to 15 kilograms can lead to marked improvement. Lifestyle adjustments like avoiding alcohol before bedtime, maintaining regular sleep schedules and managing nasal congestion can also help.

For many, however, medical intervention is necessary. Continuous positive airway pressure (CPAP) therapy is the standard treatment for moderate to severe OSA, keeping the airway open and preventing oxygen drops. Treating sleep apnea not only improves sleep quality but also reduces the long-term risk of heart disease, stroke and sudden cardiac events.

Quality of sleep is a good indicator

The most telling indicator is how one feels upon waking. Good sleep should leave a person refreshed. Persistent fatigue, morning headaches or a sense of unrefreshing sleep — even without obvious daytime drowsiness — warrants evaluation.

Today, diagnosis is more accessible than ever. Home sleep tests and specialised sleep clinics can identify apnea early, allowing timely intervention. The message is clear. When sleep is compromised, the consequences extend far beyond fatigue. In the silence of the night, untreated sleep apnea can quietly push the heart to its limits.

(Dr Shetty is lead cardiologist and medical director, Sparsh Hospital, Bengaluru)