Sleep Enough

The Relationship Between the Circadian Rhythm and Sleep

The circadian rhythm is a 24 hour periodic cycle that is adhered to by the body at all times. Circadian rhythms can be regarded as the biological clock of the body, and it comes from the words, circa, which means “around,” and diem, which means “day.” The circadian rhythms are an important part of our health, and therefore, it’s no surprise they play such an important role in sleep, given that sleep is such a regulated activity of the body.

The circadian rhythm has a direct bearing on body temperature, blood pressure, hormone production, and of course, sleep. It instructs your body to sleep, to wake up, and even dictates your emotional state at any given time. Sometimes, for no reason you might feel a little under, and at other times, you feel positive and energetic; have you considered that these have to do at least partly, with your circadian rhythm? When you abruptly switch to shift work at night, or when you have taken a long flight across continents, normally you will feel tired, and this is again due to your circadian rhythm being affected.

Rhythm is a very big part of this universe. Just think of the planets circling the sun, or the four seasons of the Western Hemisphere, or the rise and ebb of the sea tides. In sleep, there’s no escaping this influence of rhythm as well. Learning how to be in sync with your circadian rhythm can do a lot for your sleep health.

Factors affecting the circadian rhythm

In the sleeping and waking cycle, there are many biological and non biological factors that affect the circadian rhythm, such as light, temperature, sound, food, hormonal changes, and magnetic shifts. Stimuli from these sources are fed back to the hypothalamus, a part of the brain. The hypothalamus is an internal clock within the brain that manages the circadian rhythm. More specifically, it is the suprachiasmatic nuclei cells (SCN) located in the hypothalamus, which is considered to be the “master clock.”

The SCN works with all the receptors of the body to keep track of time. It has been found that light plays the most important role in telling the SCN what time it is, and when is the best time to fall asleep. Other hormones and neurotransmitters also weigh in and trigger reactions in the SCN which in turn relays all this information to the pineal gland, a tiny gland located in the brain’s center. The pineal gland is responsible for secreting almost all the melatonin (the sleep hormone) of the body.

The circadian rhythm in sleep

The pineal gland has been called the Third Eye of the body, because it is highly sensitive to light, and produces the sleep hormones in accordance to the light it receives. At the first sign of daylight, the pineal gland stops releasing melatonin, and proceeds to release pinoline instead. Upon opening the eyes and commencing of physical movement, the adrenal glands start to release cortisol, and the metabolic rate starts to increase.

The awakened state triggers other changes in the body, like an increase in body temperature and blood pressure. Conversely, when the night comes round again and it is time for bed, upon shutting the eyes and switching off the lights, the pineal gland becomes active again, and starts releasing melatonin, while the body temperature starts to drop, blood pressure falls, and the metabolic rate winds down.

Keep to a regular schedule

Constant disruptions to the circadian rhythm, like long jet flights or changing work shifts can result in sleep disorders, and uneven hormone and neurotransmitter production. It is therefore important to keep singing along to your circadian rhythm, meaning – abide by its timetable. If your usual time to sleep is 9 pm, then stick to it. If your usual wake up time is 7 am, then try to wake up at this time every day. Only by regularity, can you develop a good routine that is circadian rhythm friendly, and therefore good for your sleep health.