27:  LIGHT MANAGEMENT                                                  [Rev 1-27-2019]

Exposure to light can be used to affect both getting to sleep (Step D1, Section 46) and staying asleep (Step D2, Section 47)

Before the widespread use of electric lighting, we were mainly reliant on the presence or absence of sunlight to separate wake-time from sleep time. Our bodies still make use of light as a signal for wakefulness and sleep (Lavie, 2001), but the system can be managed. Especially, the presence of bright or blue light suggests daytime and can be used to help regulate our sleep timing

Managing light exposure can help with four different complaints:

  • Having difficulty getting to sleep at night.
  • Sleeping too late in the morning.
  • Falling asleep too early at night.
  • Waking too early in the morning.

Typically, these complaints can be paired: The person who has difficulty getting to sleep at night tends to sleep late in the morning. This is sometimes called a delayed sleep phase disorder. The person who wakes too early in the morning commonly gets to sleep early at night or takes a late nap before bed. This is sometimes called an advanced sleep phase disorder. A person’s entire circadian cycle may be either earlier or later than the cycles of other people and of the sun. (Glovinsky and Spielman 170-173, 180-182).

 

In this graph, a person with an advanced sleep phase disorder is starting to become alert before other people normally awaken, and to get drowsy before others are ready for bed. The person with a delayed sleep phase disorder becomes alert long after others are awakening, and sleepy long after they go to bed.

27a. Falling Asleep and Waking Too Late

Here the problem is to move the person’s sleep to a later period of time. Light management can be helpful at both ends of the night.

EVENING LIGHT MANAGEMENT

When a person has trouble falling asleep, we can ask whether he/she is being exposed to bright light – especially blue light – late in the day. If so, then reducing that exposure may make it easier for the person to prepare for sleep. Problems can include…

  • Being outdoors – when the days are long – until bedtime
  • Watching television until bedtime
  • Using a computer until bedtime. This is a brighter and closer source of light than a television set, and can be more problematic. People who use their laptops in bed and then try to fall asleep may have special problems here.
  • Working in a very bright space until bedtime

Blue light is one of the signals to the brain that it’s daytime and you should be awake. Using filters that block the blue range is one strategy for preparing for sleep. Glovinsky and Spielman suggest that the patient wear blue-blocking sunglasses for an hour or two before bed.

Not working on a computer can be part of this, because the bright blue light of a screen can signal daytime. Once the late-night activity is stopped, ordinary day-night sources can be more salient in managing a person’s circadian cycle.

MORNING LIGHT MANAGEMENT

For this problem, the person should use signals that the day has arrived. He/she should

  • Wake at the same time every day (Section 25)
  • Get up immediately when you awaken. Don’t lie in bed.(Section 34)
  • Turn on the lights, bright lights if possible. This will help to re-adjust sleep to an earlier time.
  • Use a light box to stimulate their vision, if that is feasible.
  • Go outdoors if at all possible. Sunlight is generally much brighter than indoor lighting.

27b: Falling Asleep and Waking Too Early

EVENING LIGHT MANAGEMENT

For this problem, the person needs to both avoid evening dozing and going to bed early.

  • Finding a way to stay awake longer at night
  • Exposure to bright light up to the beginning of preparation for sleep (the start of a buffer period – Section 18, or bedtime rituals – Section 37).

MORNING LIGHT MANAGEMENT

Lying around in bed after awakening is probably not a good idea (Section 34) because it weakens the association between bed and sleep, and the person probably can’t sleep any more, anyway.

However, it is better if person doesn’t wake abruptly to bright lights. This can mean

  • Not going outside or into brightly lit rooms until the desired wake time
  • Blocking blue light using sunglasses for a while.

27b. During the Day

It is generally beneficial for a person to be exposed to bright light during the day, especially outdoors. Problems here can include

  • Working indoors, in a dimly lit room.
  • Not getting outside enough