Getting too little — or even too much — sleep could be putting your health at serious risk. Cardiothoracic surgeon Dr Jeremy London, who has over 25 years of medical experience, has warned that chronic sleep imbalance may increase the likelihood of heart disease, type 2 diabetes and certain cancers.
In a recent social media video, Dr London explained that the relationship between sleep and health follows a “U-shaped curve.” According to him, sleeping fewer than six hours a night significantly raises health risks. However, regularly sleeping more than nine hours may also be harmful. The ideal duration, he said, lies between six and eight hours of quality sleep.
He highlighted the importance of the body’s circadian rhythm — the natural internal clock that regulates sleep and wake cycles. Humans are biologically wired to wake with sunlight and sleep after sunset. Disrupting this rhythm can affect hormone production, appetite control, mood stability and stress levels. Many people experience cravings, irritability and mental fog after a sleepless night — early warning signs of hormonal imbalance.
While one bad night of sleep is unlikely to cause lasting damage, Dr London stressed that long-term sleep deprivation can have serious consequences. Over time, poor sleep patterns may contribute to cardiovascular disease, metabolic disorders and increased cancer risk.
Calling sleep “foundational” to overall physiology, the surgeon urged people to prioritise consistent and restorative rest. For long-term health protection, maintaining a steady routine of six to eight hours of sleep each night may be one of the simplest — yet most powerful — lifestyle changes.