But medical experts say telltale signs can emerge weeks before the event - yet more people fail to recognise them. Dr Gross explained that the body frequently compensates before a complete blockage develops. Dr Gross noted that timing also matters and certain hours carry greater risk. "Sleep disruptions caused by symptoms which recur nightly or continue despite low amounts of physical exertion are not normal for ageing," Dr Gross cautioned. Many women experience less commonly recognised symptoms like unexplained tiredness, nausea, shortness of breath, or jaw, back or upper abdominal discomfort instead of well-known symptoms like crushing chest pain.