How Does Light Impact our Sleep/Wake Cycle?

Light is a strong signal of time of day to our circadian rhythms, 24-hour cycles in physiology and behaviour which are driven by an internal clock. One example is our sleep/wake cycle but there are in fact rhythms in nearly all aspects of our physiology and behaviour including our metabolism and the production of certain hormones.

Light exposure to the retina is first relayed to the suprachiasmatic nucleus (SCN) of the hypothalamus which is our principal circadian pacemaker. This signal then descends to the pineal gland (located in the epithalamus) which transduces signals from the sympathetic nervous system into a hormonal signal. Resulting from this is the production of hormones such as serotonin (the "happy" hormone) and melatonin (the "sleep" hormone). This biological process adjusts the body's circadian rhythm so that the internal and external day coincide. When our circadian rhythm becomes out of sync with our desired sleep/wake schedule, we can experience disrupted sleep patterns and a decline in our overall sense of well-being. So, how can we use light therapy to help keep our rhythm in sync?

The circadian rhythm of most people is slightly longer than 24 hours and so in order to remain synchronised to local time and to ensure good quality sleep at the desired time, it requires a morning light cue. During dark winter mornings (and early mornings post-March clock change) when this cue is absent, a bright light therapy lamp can be used upon waking to help keep your circadian rhythm in sync and your sleeping patterns consistent. For those looking to shift their sleep time earlier, bright light in the morning can be beneficial, and for those who intent to shift their sleep time later, exposure to a bright light therapy lamp in the early evening can help to achieve this effect. For this reason, it is important to be mindful of your light environment in the evening as exposure to bright light can make it difficult to fall asleep.

Lumie sunrise alarm clocks help you to optimise the light environment in your bedroom for sleep. When it comes to bedtime, they gently fade through the colours of a sunset to promote your body’s natural sleep response, allowing you to drift off easily into rejuvenating sleep. When morning comes around, they rouse you from sleep gently with gradually brightening light, rather than jolting you awake like a regular alarm clock. During this process of steadily brightening light, your heart rate and core body temperature gradually rise, emulating the body’s natural physiological response to dawn so that you feel refreshed by the time you open your eyes.

Bright light therapy lamps help to improve our mood, energy and alertness and serve as an effective treatment for winter blues. During the bright, summer months, many of us experience a boost in our overall sense of well-being due to our exposure to sunlight which influences our body chemistry, including the levels of melatonin and serotonin. When daylight hours are limited and time spent indoors increases, many of us experience fatigue, sluggishness and irritability due to inadequate exposure to light. By mimicking the brightness of natural daylight, bright light therapy lamps offer the mood-boosting qualities of sunlight. It is important to seek advice from a medical practitioner if you are experiencing persistent low mood.