Sleeping in on weekends may feel like a harmless treat but experts warn it could disrupt the body’s natural rhythms and even harm mood and health.
“It’s a common ritual: turn off the alarm, stay in bed a little longer and think every extra hour counts,” said Prof. Tzipi Strauss, director of the Longevity Center at Sheba Medical Center. “But oversleeping can confuse the biological clock, affect energy and leave people waking irritable or moody.”
Humans have an internal biological clock influenced by genetics. Receptors in the hypothalamus respond to light and darkness while sensors in the eyes trigger the release of melatonin, the sleep hormone, along with other hormones and body temperature changes.
Chronotypes, or natural sleep patterns, also play a role. “Morning types wake and sleep early and reach their energy peak in the morning. Evening types wake and sleep late and are more productive at night. Young people are often evening types,” Strauss said. Evening types may experience slightly higher rates of depression or obesity but can also exhibit more creativity. About 15% of people are extreme cases at either end of the spectrum, she said.
Strauss highlighted a growing concern known as “social jet lag,” where a person’s biological clock conflicts with social schedules like work or school. “About a third of the world suffers from social jet lag with a mismatch between their natural rhythm and daily life,” she said. Some countries have even delayed school start times to better align with students’ internal clocks.
Research shows misalignment can increase risks of anxiety, depression, obesity, cardiovascular disease and neurodegenerative illnesses such as dementia, Strauss said.
Weekend “catch-up sleep” is often counterproductive. Studies of 15,000 people in South Korea suggest that one to two hours of additional sleep is optimal. More than that can increase irritability, anxiety and depressive symptoms, particularly in women over 50 and young people who sleep little during the week. Less than an hour of catch-up sleep is also ineffective.
Prof. Tzipi StraussStrauss recommends aligning daily schedules with individual biological clocks. Evening types should plan activities and meetings in the evening while morning types should schedule early. “Consistency is key,” she said. “Extreme changes to the body’s internal clock are nearly impossible and can be harmful.”
Sleep hygiene also matters. Strauss advised limiting exposure to blue light from screens in the evening, avoiding caffeine six to eight hours before bedtime, steering clear of vigorous exercise or heavy meals near sleep and keeping bedrooms dark and cool. Regular sleep schedules—going to bed and waking at the same time daily—are essential for quality rest.
Sleep disorders fall into two main categories: mechanical issues such as sleep apnea which disrupt nightly rest and insomnia where people cannot fall or stay asleep. At Sheba’s Longevity Center, patients are diagnosed and guided on sleep hygiene and routines.
“Good sleep is not a luxury—it’s vital for health,” Strauss said. “Consistency and awareness of your natural rhythm are crucial to feeling rested and maintaining well-being.”