Regulating Sleep: How Light Therapy and Blue Light Blocking Glasses Influence Circadian Rhythms

This podcast episode, hosted by Dr. Tracey Marks, delves into the profound influence of light on the human circadian rhythm and its practical applications for managing various sleep disorders. The core mechanism explained is that light exposure directly triggers the shutdown of melatonin production in the brain, a process that can be strategically manipulated to reset the body's internal clock. The discussion highlights the effectiveness of bright light therapy, primarily through commercially available light boxes that mimic sunlight's wavelength without harmful UV effects, for conditions such as delayed sleep phase disorder, jet lag, and shift work sleep disorder. Conversely, light-blocking glasses are introduced as a tool to prevent unwanted wakefulness, particularly useful for shift workers needing to sleep during the day or individuals struggling with early evening sleep due to circadian disturbances.

The episode provides a detailed case study of "Milton," a self-proclaimed night owl with delayed sleep phase disorder, to illustrate the application of light therapy. Milton's struggle to adjust to an early morning work schedule despite adhering to sleep hygiene rules underscores the biological basis of his condition. The solution involves using a light box for 30 minutes each morning upon waking to signal to his brain an earlier start to the day, thereby shifting his sleep-wake cycle forward. Additionally, Milton's habit of late-evening outdoor activities, which inadvertently perpetuated his night owl tendencies by exposing him to light, is addressed by the recommendation to wear blue light blocking glasses in the early evening to reduce melatonin suppression.

Practical insights and recommendations are meticulously outlined for both delayed and advanced sleep phase disorders. For those struggling to fall asleep too late (delayed sleep phase), the advice is to use a light box for 15 to 45 minutes within the first hour of waking, positioned at an arm's distance and 45 degrees to the eyes. For individuals falling asleep too early (advanced sleep phase), bright light exposure is recommended 3 to 4 hours before the desired bedtime. The portability of light boxes is emphasized, allowing users to integrate therapy into their morning routines. The episode also details the specific design of blue light blocking glasses, often with orange lenses, and their utility in mitigating the impact of electronic devices and late-evening outdoor light exposure on melatonin secretion.

Finally, Dr. Marks addresses potential side effects and contraindications of bright light therapy. While generally considered safe with minor reported side effects like eye irritation or headache, it is strongly advised to start slowly with shorter exposure times and consult a doctor before use. Specific warnings are issued for individuals with light-sensitive skin or eyes, those taking photosensitizing medications, and people with bipolar disorder, who should avoid light therapy entirely or use it only under strict medical supervision. This comprehensive approach underscores the importance of understanding individual circadian rhythms and applying targeted light interventions responsibly to optimize sleep health.

Light has a strong influence over the timing of your circadian rhythm remember light triggers the shutdown of melatonin in your brain so we can use this to our advantage when trying to regulate sleep problems or reset your body clock

Sunlight is the best type of light to trigger a resetting of your internal clock but sun lights not always available for the purposes of treatment so fortunately there are commercially produced light boxes available

Remember light wakes you up and the dark makes you sleepy the glasses block the light that triggers wakefulness these are helpful for shift workers who need to sleep during the day or people who can't fall asleep in the early evening due to a disturbance in their body clock

Milton has delayed sleep phase disorder meaning that he doesn't even begin to get drowsy until the early morning hours and even when he attempts to force himself to fall asleep earlier and abides by proper sleep hygiene rules, he still feels wired.

If your problem is falling asleep too late and you want to move up your bed time use a light box for 15 to 45 minutes within the first hour of waking up.

Because these these boxes are portable you can move around with them get yourself ready in the morning prop it up brush your teeth so you don't have to be fixed and sitting in some position for fifteen or thirty minutes every single morning you can move around with it.

These glasses can be very useful in the summer time because if you're spending a lot of time outside in the summers later in the evening the sun exposure is like getting light therapy at night and it can actually push back your bedtime by pushing back your melatonin release making it harder for you to fall asleep.

Bright light therapy has not been shown to have any major side effects though some people have reported minor side effects including eye irritation, dryness, headache nausea, dryness of the skin

The following people should avoid it entirely or use it only under a physician's direction. That would be anyone with skin or eyes that are highly sensitive to light, anyone taking medications that increase the risk for photosensitivity. People suffering from bipolar disorder