Staying up late has quietly become normal. Work deadlines, screen time, binge-watching and late dinners often push sleep well past midnight. But cardiologists warn that consistently living like a “night owl” may be doing more than just making you tired; it can increase long-term heart risks.
According to Dr Rushikesh Patil, Associate Director – Cardiology at Dr L H Hiranandani Hospital, Powai, irregular and late-night sleep disrupts the body’s internal clock and sets off a chain reaction that affects blood pressure, metabolism and heart health.
How late-night sleep disrupts the body’s circadian rhythm
The word circadian comes from Latin, meaning “around the day”. This internal clock regulates when we feel sleepy and when we feel alert. “When we stay awake late into the night with lights and screens on, the brain gets confused,” Dr Patil explains. “It delays the release of melatonin, the hormone responsible for initiating sleep.”
Deep, restorative sleep typically occurs earlier in the night. When bedtime shifts later, sleep quality suffers even if the total hours seem adequate. This usually causes drowsiness during the daytime, lack of concentration, irritability, and mood swings.
What poor sleep does to blood pressure and the heart
Normal sleep helps the blood pressure drop naturally for several hours straight. This is a nightly process that is important for the heart. “Inadequate or irregular sleep keeps stress hormones like cortisol elevated and activates the sympathetic nervous system,” says Dr Patil. “This leads to persistently higher blood pressure.”
Over time, poor sleep increases inflammation and damages blood vessels, making arteries stiffer. This raises the risk of heart attacks and strokes. Sleep deprivation is also linked to abnormal heart rhythms, ranging from occasional skipped beats to dangerous arrhythmias that need medical attention.
The sleep–weight–diabetes connection
Poor sleep and weight gain often fuel each other. “When sleep is disrupted, appetite-regulating hormones go out of balance,” Dr Patil explains. Ghrelin, which stimulates hunger, increases, while leptin, which signals fullness, drops. This leads to cravings, overeating, and weight gain.
This hormonal imbalance leads to increased levels of blood glucose and an increased risk of insulin resistance and type 2 diabetes mellitus. According to studies, individuals who sleep less have a 30 per cent higher risk of acquiring diabetes than those who sleep well.
Conditions that place extra pressure on the heart include high sugar levels, being overweight, inflammation, and hypertension.
Are night owls at higher risk of heart disease?
Large-scale research supports this concern. A UK Biobank study involving more than 300,000 adults examined the impact of different sleep chronotypes.
“Night owls were found to have significantly poorer cardiovascular health,” says Dr Patil. “They showed a 16 per cent higher risk of heart attack or stroke over about 14 years compared to intermediate sleepers.”
Night owls were also more likely to smoke, experience sleep deprivation, have irregular schedules and get inadequate morning sunlight, all of which disturb circadian rhythm further.
However, Dr Patil emphasises that being a night owl does not automatically doom heart health. “Those who maintain adequate sleep duration, manage stress and follow healthy lifestyle habits can significantly reduce their risk.”
How much sleep does the heart really need?
The American Academy of Sleep Medicine recommends:
- Adults: 7 to 9 hours of sleep
- Children (6–12 years): 9 to 12 hours
- Adolescents (13–17 years): 8 to 10 hours
Sleeping fewer than six hours as an adult is considered insufficient and harmful over time.
Equally important is consistency. “Going to bed and waking up at roughly the same time every day, including weekends, helps stabilise the circadian rhythm,” Dr Patil says. Late nights may feel harmless, but chronic sleep disruption quietly raises blood pressure, worsens metabolic health and increases cardiovascular risk.
Good sleep is not a luxury. It is a protective tool for the heart. Aligning sleep with your body’s natural clock, prioritising consistency and ensuring enough hours may be one of the most powerful lifestyle changes you can make for long-term heart health.
Disclaimer: Tips and suggestions mentioned in the article are for general information purposes only and should not be construed as professional medical advice. Always consult your doctor or a dietician before starting any fitness programme or making any changes to your diet.
