Chronobiology and personalized light
Chronobiology is gaining importance in the understanding of human physiology. The innate rhythmicity of biological functions, where most fluctuate according to a circadian rhythm, thus prepare the body for daily recurring events such as eating and sleeping. The pancreatic clock regulates insulin secretion and its response to glucose; the hepatic clock regulates glucose clearance, the skeletal muscle clock regulates metabolism and glucose uptake, and so on³⁶. The suprachiasmatic nucleus in the hypothalamus is the synchronizer for all of the clocks in the body. It adjusts the production of hormones such as melatonin and cortisol. The timing of these processes is collectively called our circadian rhythm. Recent evidence points to a genetic variability of clock genes associated with individual differences in sleep and circadian physiology and non-visual response to light³⁷.
What is a circadian rhythm?
Circadian rhythms are the result of an adaptation to earth’s rotation applying a 24 hour structure on bodily physiology. Humans are genetically programmed to be diurnally active. The body with its physiology and metabolism organized around 24 hours is optimally functioning when this rhythm is paced daily by light. Light is the most important synchronizer for the circadian rhythms in the body. Many of the bodily functions, such as sleep, hormones and metabolism vary with the daily cycle given by day and night. The innate rhythmicity of biological functions, where most fluctuate according to a 24 hour circadian rhythm, prepare the body for daily recurring events such as eating and sleeping.
What is a chronotype?
It is evident that modern lifestyles vary significantly in relation to the natural light-dark cycle and influence our access to daylight. Eating habits, when, how and if we choose to exercise, travel schedules and work commitments all affect the bodily rhythms. These parameters are individual. People differ and so do their needs. The same light environment is registered by the circadian system very differently between individuals. People have different chronotypes that translates into their preferred timing of sleep and wake. Certain genes have been linked to morning-evening preference and genes that generate and regulate sleep and circadian rhythms are important for understanding the individual variances in sleeping behavior. The BioCentric Lighting™ system is easily customized according to the unique needs of the individual and the situation. The light environment provides adaptable light to fulfill the biological need for each day, regardless of season.
Most people have a circadian rhythm that is slightly longer than 24 hours
People with a circadian rhythm period above the average are people are commonly described as night owls and those with shorter period considered morning larks.
Night owls are have a circadian rhythm period above the average. They tend to be more energetic in the evenings and can easily stay up later than average. They also have more difficulties waking up in the morning. Night owls would benefit from a light exposure that helps them wake up early in the morning to match their spontaneous wake up time with their work schedule. They would then also feel sleepy earlier in the evenings.
Morning larks have a shorter circadian rhythm period. They easily wake up early in the morning – which may lead to insufficient sleep if they need to stay up late at night. The right light exposure would help these individuals keep their alertness level a little longer in the evening and get more quality sleep, up until the time they should wake up.