In addition to reducing lights and screen time in the evening to help you transition from wake to sleep, exposure to lights during the morning and throughout the day is just as important for maintaining a healthy sleep-wake circadian rhythm. Bright lights in the morning will not only generate an alerting affect in the brain, it will also attenuate the production of melatonin, an internal hormone produced at night indicating to your body that it is ‘night-time’.
Exposure to light early in the morning also has beneficial effects come evening time, making it easier to transition into sleep due to the phase shifting effects of early bright light exposure on our circadian rhythm. Specifically, the majority of individuals tend to have a delayed circadian rhythm (start and end later in the 24-hr day/night cycle). This stems in part from natural tendencies of our biological clocks to be longer than that of the 24-hr cycle, as well as the fact that we are typically exposed to lights in the evening further delaying our internal biological rhythms, such as the production of melatonin.
Being exposed to bright lights in the morning, right after waking up will consequently help to shift the biological clock forward, offsetting the effects of the evening light. This is similar to what we observe in the spring daylight saving’s time (‘Spring Forward’) where we shift the environmental clock forward an hour, except in this case it is the biological clock rather than the environment. This shift in our internal circadian rhythm will not only makes it easier to wake up at the desired time, but will also shift the tail-end of the cycle, making it easier to fall asleep come bed-time.
However, flickering on the bright lights or drawing the blinds right after waking up, specially when the room is dark, can be hard on the eyes due to the light adapting response of the photoreceptors within our eyes. Although this is not harmful per se, it is an unpleasant blinding sensation. Instead, look to slowly expose yourself to the bright lights, such as by gradually drawing the blinds or by starting off with a softer bedside lamp to avoid an abrupt transition. Nevertheless, this transition from dark to bright lights should be done within the first few minutes after waking up to further help your brain and body transition from sleep to wake.
Sunlight is the preferred option as the overall level of brightness and illumination (lux) exceeds that of interior lighting, even on cloudy and overcast days. Therefore, look to get as much sunlight as possible in the morning and day time. However, although sunlight exposure is easily accessible throughout the summer months, it can be difficult to obtain adequate exposure, particularly in the morning, come winter time as many of us need to wake up before dawn. When natural light is limited, look to optimize internal lighting to make for an easier morning process and routine. For example, look to use lamps or indoor lighting with a higher proportion of blue light (such as ‘daylight’ or ‘cool white’ LED bulbs) in the morning and daytime, but remember to reduce these come evening time.
Overall, in the morning period, the faster we can switch from a biologically sleep inducing state to a wake promoting state in the morning time, the better regulated and the more robust is our internal biological clock.