Grow Youthful: How to Slow Your Aging and Enjoy Extraordinary Health
Grow Youthful: How to Slow Your Aging and Enjoy Extraordinary Health

Body Clock - the best time of day to eat, think, work, exercise, sleep


Your brain has a clock that knows exactly where you are in the 24 hour day. Most of your other organs also have an internal clock and daily rhythms. The time of the day strongly affects how your body, your mind, and each of your organs performs. When is the best time of day to exercise? What time of day is your concentration the best? Best time for meals? Is there a high-risk time of day?.

6am - 10am

When you wake in the morning your metabolism is slow. Your blood vessels are constricted after sleeping, so your blood pressure is high as you start your day. Your blood platelets are measurably "sticky". At this time exercise actually increases your blood pressure, so it is best not to do any heavy exercise. This is the time of the day when most heart attacks occur.

It is best not to eat food within 30 minutes of rising. If you have breakfast try to have some protein foods with it. My book Grow Youthful discusses why this is important.

Sunlight, both on your skin and through your eyes, wakes your body and its clocks. Plenty of sunlight in the morning will help you to wake early. If you are waking too early in the morning, then avoid bright light in the morning and instead try to get your sunlight in the middle of the day.

Sufficient sunlight during the day will help you sleep better at night, gives you better brain function, decreases your risk of Alzheimer's disease, and has many other benefits.

Men often tend to wake with an erection, and their testosterone level is highest at this time of day. This is the time when they may feel the most sexual and have the strongest desire. Male testosterone levels fall as the day progresses.

Women are built differently. They tend to wake with low levels of sex hormones, and it may not be until 9:00 or later before they have any innate sexual desire. As the day progresses, their sex hormone levels generally increase, with a peak in the 4-6 or 6-10 pm time slot.

10am - 12 noon

This is the time of your mental peak. Your concentration, memory, focus and creativity should be best at this time of the day. Use this period to do that work that needs your best thinking, rather than using it for other tasks.

Balance and muscle control are best at this time in the morning. However, the best time for exercise is in the afternoon.

12 noon - 2pm

Most people have lunch in this period. Notice how you may feel sleepy after lunch? Our paleolithic ancestors probably had a nap at this time, and many cultures and traditional communities still do. You can benefit from a short sleep or a catnap too.

2pm - 4pm

This is a time for activity. Blood vessel dilation is poor in the morning, and exercise actually increases blood pressure. However, by the early afternoon your blood vessels are starting to dilate, and exercise has the effect of decreasing blood pressure. Your body temperature is highest during the afternoon.

4pm - 6pm

This is the best time for exercise. Athletes can get up to 10% better times and performance during this period of the day. Your blood vessels are most dilated, your body temperature is highest, and exercise is the most beneficial for your body, having the effect of noticeably decreasing blood pressure. Your body is most resilient, and the fewest heart attacks are recorded at this time of the day.

6pm - 10pm

People generally have their dinner in this period, and continue with other more social activities. However, it is not a good time to have a large meal requiring a lot of digestive power, within just a couple of hours of going to bed. (5) Insulin is not as effective at night as it is during the day. Protein digestion is inefficient at night while you are sleeping. Good reasons not to eat late in the evening.

If you drink alcohol, this is the best period in which to drink. You should be well awake at this time, and less likely to be affected (depressed or sleepy) from drinking the alcohol.

10pm - 12 midnight

Most people go to bed in this time slot. If you find you are not able to get to sleep until late at night, then get more sunlight during the day, especially in the morning. Bright light late in the day tends to waken you for the next few hours.

If you are a night owl rather than an early bird, you are at increased risk of a variety of diseases, likely to die earlier, and likely to perform less than optimally.

12 midnight - 3am

People are entering deep sleep. If you have not gone to bed by this time, you should feel tired.

3am - 6am

This is the low time of your metabolism, with 4 am usually being the lowest point. At this time most people have the lowest blood pressure, the highest blood viscosity, and the highest blood platelet stickiness.


1. Atkinson G., Speirs L. Diurnal variation in tennis service. Perceptual & Motor Skills 86, no. 3 part 2. June 98, 122-127.

2. Bishop D. The Effects of Travel on Team Performance in the Australian National Netball Competition. Journal of Sports Science and Medicine 7, no. 1, March 2004. 118-22.

3. Baxter C., Reilly T. Influence of time of day on all-out swimming. British Journal of Sports Medicine 17, no. 2 (June 1983): 122-27.

4. Sedliak M., T. Finni, S. Cheng, W.J. Kraemer, K. Hakkinen. Effect of time-of-day-specific strength training on serum hormone concentrations and isometric strength in men. Chronobiology International 24, no. 6 (2007): 1159-77.

5. R. Pamplona. Mitochondrial DNA Damage and Animal Longevity: Insights from Comparative Studies. Journal of Aging Research, 2011. DOI: 10.4061/2011/807108.