Age and Circadian Rhythms Decide the Best Times to Eat, Sleep, Wake and Exercise

Depending on our age, there is a best time to do everything — from sleeping and waking to eating and exercising.

Circadian rhythms are behavioral, mental and physiological changes governed by the body within a 24-hour clock. Influencing our body temperature, hormone release, sleep/wake cycles and other important functions, they change, as we get older. Environmental cues like sunlight, darkness and temperature also affect them.


Since those in their twenties stay up late, dinner around 9:30 pm serves as an energy boost. An 8 pm meal is ideal for those in their thirties and forties. To avoid heartburn, people in their fifties should eat dinner around 7 pm and those in their sixties, around 6:30 pm to get optimal time to digest their food.


Exposure to light is a signal for the brain to raise body temperature and produce cortisol while delaying the release of melatonin. Stress and natural circadian rhythm cycles trigger the production of cortisol to boost energy levels in the morning, which decrease throughout the day. Produced on exposure to darkness, melatonin is associated with sleep. Its levels rise in the evening and remain high throughout the night, promoting sleep and starts decreasing, as we get older.

The ideal wakeup time when we are in our twenties is 9:30 am, 8 am in our thirties, 7.30 am in our forties, 7 am in our fifties and 6.30 am in our sixties. To ensure that we get the rest we need, we need to adjust our bedtime to match our wakeup time. Adults must get 7–9 hours of sleep and older adults (65+) should sleep for 7–8 hours.


Circadian rhythms affect our ability to focus and perform. Sleep inertia and grogginess disappear 2.5–3 hours after waking up, which is the best time to start work since we are extremely alert. This is around noon for those in their twenties. Since neither schools nor work starts this late, we have become a ‘do more and sleep less’ culture.


The optimal time to work out is around four hours before bedtime. This is when our lung function and strength are at their peak. It would be around 7 pm for those in their thirties, 6 pm for those in their forties, and around 5 pm for those in their fifties. The same holds true for liver function as well. Since it decreases with age, we must give our body at least four hours before bedtime to process alcohol.

Circadian rhythms are extremely useful regulators of bodily functions. We must listen to our body to engage in certain activities at optimal times to enjoy the most efficient and healthy outcomes.

Like what you read? Give HealthSignz a round of applause.

From a quick cheer to a standing ovation, clap to show how much you enjoyed this story.