delivered at varying intensities in convenient locations
throughout the living environment. Even modest lighting
remedies — such as brighter floor and wall lamps during
waking hours — can help reduce symptoms of agitation and
dementia in long-term care settings, as Figueiro and colleagues
found (Clinical Interventions in Aging, 2014).
One groundbreaking study showed that brighter fluorescent
lights in common areas in nursing homes had a positive effect
on cognitive function in Alzheimer’s patients in managed-care
settings, as well as lessening symptoms of depression, compared
with residents who received less light (JAMA, 2008). Another
study by Figueiro and colleagues that tested bright overhead
lighting for people with dementia living at home also found
that the intervention reduced symptoms of depression in
patients, and helped them sleep more regularly and efficiently
(Sleep Health, in press).
“I have no question that if you deliver the right light in
Adolescents and sleep
Alzheimer’s patients you will improve their behavior; you will
improve agitation; they will sleep better,” says Figueiro. “The
She has also developed a 24-hour lighting scheme for older
adults for the American Institute of Architects. Its strategies
include the use of bright table lamps by day and dimmer,
yellowish white illuminated door frames at night that can help
Adolescents are particularly sensitive to light-dark cycles.
Beginning in early puberty, melatonin levels in the body start
to peak later and later at night, significantly pushing back the
time when adolescents feel sleepy. Because most teens need to
wake up early for school, those late nights significantly decrease
their total sleep time, which can lead to a number of issues
including worse academic performance in school and mood
problems. Delayed sleep times are also associated with seasonal
affective disorder, which can affect teens as well as adults.
Teens’ nighttime use of brightly lit computers and
smartphones can make it even harder for them to fall asleep.
In her research, Figueiro found that computers and laptops
suppressed melatonin in 15- to 17-year-olds more than in
the general population. Even one hour in front of a screen
decreased melatonin levels by 23 percent (Lighting and Research
Come morning, adolescents may face more circadian
challenges if they lack enough bright light to start their days.
In some seasons, children are in school before the sun rises, so
they miss out on the morning daylight. That could affect their
Rensselaer colleague Mark Rea, PhD. They found that teens
whose intake of bright light was artificially dimmed during the
morning with blue-light blocking glasses took longer to fall
asleep at night (Neuro Endocrinology Letters, 2010).
Yet those same glasses could prove useful in the evening.
In a study of 13 students ages 15 to 17, Stéphanie van der Lely
of the University of Basel and colleagues found that blue-light blocking glasses decreased screen-induced melatonin
suppression and led to self-reported increase in sleepiness
compared with a control group that did not wear glasses
(Journal of Adolescent Health, 2015).
Another study found that a dose of bright white light at
home in the morning may give adolescents a boost to better
handle the day ahead. Figueiro and Rea exposed 18 sleep-restricted adolescents ages 12 to 17 to 80 minutes of short-wavelength light after the teens woke. The teens’ saliva samples
showed that the light increased levels of the energy boosting
hormone cortisol compared with when they were exposed to
dim light (International Journal of Endocrinology, 2012).
Waking to a simulator that gradually brightened a room —
much like the rising sun — also showed benefits, improving
teens’ performance on cognitive tests, according to a study
of 56 teenagers by psychologist Lorenzo Tonetti, PhD, of the
University of Bologna and colleagues (European Journal of
Applied Physiology, 2015). The tool should appeal to parents
and educators, Tonetti says, because within a relatively short
time — 20 minutes each day over two weeks — the inexpensive
simulator had a positive alerting effect, though future research
should investigate whether either a prolonged or cyclical use of
the device is even more effective.
The 15 million people who work at night in the United States
face even more serious issues due to circadian misalignment.
Humans evolved to be awake during the day, but many night
shift workers must sleep days and stay up nights. Long-term, that disruption can have many health consequences. As
psychologist Charmane Eastman, PhD, and Mark R. Smith,
PhD, of Rush University Medical Center, wrote in a 2012 review
for Nature and Science of Sleep, shift workers are at a greater risk
for cardiovascular disease, being overweight and reproductive
problems. The International Agency for Research on Cancer
recently classified shift work as a “probable carcinogen.” A
relative lack of melatonin, a natural antioxidant, may be one
mechanism that explains shift workers’ increased risk of cancer,
according to the review.
While stimulants, sedatives and melatonin supplements
can induce alertness or sleep in night workers in the short
term, the best way to reduce the health risks may be to
enforce a full circadian shift with a longer-term light-dark
plan that includes black-out curtains and masks for sleeping
and at least one hour of electric bright light while working,