Unpacking Circadian Rhythms And Sleep Patterns

Have you ever noticed that your waking and sleeping patterns tend to work in a set pattern? The reason for this is that the body runs on a number of different circadian rhythms. The blood pressure varies of 24 hours, as does the pulse rate, the body temperature, all hormones, bone growth, immunity, tissue repair, and so on.

According to Dr K.D. Rosman, specialist neurologist at the Morningside Sleep Clinic in Sandton, Johannesburg, circadian rhythms are all controlled in the same way that sleep is. “When we are exposed to bright light in the morning, and most specifically in the blue light spectrum, this suppresses the production in the body of a hormone called melatonin,” he explains. “The light intensity required is approximately that which one would get in the shade of a tree. Generally speaking, indoor lighting is not bright enough. When light dims at the end of the day, melatonin production peaks, and this will put us to sleep a few hours later.”

So where do our problems come into play?

Since the invention of electricity and the lightbulb, our quality and length of sleep has deteriorated at a steady rate, because our bodies keep being exposed to light, which keeps us awake beyond the natural time to go to bed.

“From time to time we will all push the boundaries of our circadian rhythms,” Rosman says. “Doing this for one or 2 nights will generally not cause a problem. However, if we are going to work for 18 hours a day for a longish period, this is going to cause significant problems in terms of our sleep, but also in terms of all the other circadian cycles. For example, the blood sugar will tend to increase, our memory will become a problem, and we will tend to become moody if not frankly depressed.”

So how do we correct this?

“The simplest way to get back our rhythms, is to allow ourselves to shift back into the natural 24-hour cycle. In other words, keep your bedtime and wake time consistent,” he explains. “Bearing in mind that the average required sleep time for a young adult is roughly 7 1/2 hours, but this will be considerably more for a younger person, and will tend to become less as we get older. We need to “wind down” from the stresses of the day before we get into bed. In order to do this, some non-stress-related activity, such as a hobby, is good to do after dinner. For about the last 30 minutes or so before getting into bed, one should do the regular bedtime routine. Because this is the same thing every night, it becomes a little bit “mindless”, which allows the brain to wind down towards sleep.”

In newborn children the circadian problem is slightly more complicated.

“When we sleep – as an adult – we will sleep in 90 minute cycles. At the end of that time we wake, roll over and go back to sleep, but will not have memory for waking. In the newborn the cycle is around 60 minutes. However, the child does not “know” to go back to sleep after waking, and will then wake its parents. Once the child learns that the waking is completely normal, then the night-time problems tend to settle,” Rosman says.

“A young child may need 20 hours or more of sleep per day. In order to allow this to happen, routine is the key. A regular bedtime is important (at any age). The bedtime bath and storytime is important to allow the child to wind down towards sleep. Regular waking time in the morning is important. If a nap is required during the day, this should be done at a regular time. Feeds, if possible, should be done at a regular time. Exposure to bright light in the morning will help to establish the sleep cycle, and the bedroom should not be brightly lit at night.”

With jetlag, the 24-hour cycle is disrupted because of the changed (experienced) time of sunrise and sunset.

“Each of the cycles I have mentioned above will recalibrate itself at a different rate,” he explains. “However, on average, you can bargain on correcting the rhythm by approximately one day for every hour time change. In the course of this correction, the cycles will run out of synchronicity, with resultant problems. So, for example, people may become irritable in this time, the memory may be affected, and they will tend to fall asleep irresistibly at inconvenient times. Exposure to sunlight in the morning, and the addition of melatonin in the evening for one or 2 nights will help speed up the adaptation of the body to the new light/dark cycle.

Shift work is, and always will be, a problem. The issue is that every time the work cycle is shifted, one is, in effect, imposing jetlag. To make matters worse, when these people are trying to sleep the rest of the community is awake and making noise, and it becomes hotter, which is more difficult to sleep in. Furthermore, there are social pressures, such as from the spouse, which all conspire to reduce the total sleep time available to the individual. This then has all the expected consequences, as indicated above. Generally speaking, the time between shifts is too short to allow adequate acclimatization, and many shift workers will find themselves in a poor state of health after only a few years of working shifts.”

Harvard Health has a word on how to reset circadian rhythms to minimize jetlag, which you can read here.

Should your sleep pattern mach your partner’s? Read our take here.