The human body runs on a 24 hour cycle that is managed by our master biological clock. And this master biological clock is located in a region of the brain called the hypothalamus. Biological clocks produce the circadian rhythm and regulate its timings. Above all, the circadian rhythm tells you when to eat, sleep, and wake up. In addition, an individual’s circadian rhythm dictates whether to sleep early or late as well as whether to get up early or late.
Most noteworthy, studies show that people who sleep later tend to have unhealthy diets. Also, compared with people who sleep earlier, the late sleepers drink more alcohol, eat more sugar, drink caffeinate drinks and eat fast foods. In addition, the late sleepers are likely to miss breakfast and eat later in the day. Also, their diet contains less grains, rye, and vegetables. And, they eat fewer, but larger meals.
Above all, studies also indicate that eating later in the day is associated with increased risk of type 2 diabetes. And studies indicate this is because of the way the circadian rhythm metabolizes glucose. Especially relevant, the natural tendency is for glucose levels to decline throughout the day reaching the lowest point prior to going to sleep. However, late sleepers eat shortly before bed, thereby, increasing their glucose levels just before going to sleep. And this negatively affects their metabolism.
Also, a recent study in Advances in Nutrition found that conditions such as heart disease and type 2 diabetes are associated with people who sleep late.
Meanwhile, other studies indicate that you get more Non Rapid Eye Movement (NREM) sleep between 11 PM to 3 AM and Rapid Eye Movement (REM) sleep between 3 AM and 7 AM.
- So, if this pattern applies to you, the early sleeper will get more NREM sleep and less REM sleep
- And conversely, the late sleeper will get less NREM sleep and more REM sleep
Most of all, NREM Stage 3 deep sleep (sleep that is most beneficial) occurs in the first two to three hours of sleep – or, in effect, the first two 90 minute sleep cycles. However, most of the deep sleep typically occurs in the first sleep cycle. As a result, the best time to sleep is about 10 to 15 minutes before 11 PM. And wake up 8 hours later. In this scenario you would get the most NREM and REM sleep.
On the other hand, if you are a real early sleeper (say by 9 PM), you may not get the best NREM Stage 3 deep sleep. And if you get up by 5 AM you only get 2 hours of REM sleep instead of a possible 4 hours.
Moreover if you are a late sleeper, and have to get up early for work your sleep gets disrupted. And, the infographic below illustrates the effects of this disruption.
In summary, sleeping early gets you the most benefits from sleep and you benefit from being healthier. And if you are a late sleeper, you not only don’t get the most benefits from sleep, but your health suffers.