The Effects of Bright Light Exposure on ICU Nurses
| Status: | Completed |
|---|---|
| Conditions: | Insomnia Sleep Studies |
| Therapuetic Areas: | Psychiatry / Psychology |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 12/16/2018 |
| Start Date: | October 15, 2017 |
| End Date: | December 31, 2017 |
In the majority of intensive care units, nurses work 12 hour shifts that consist of days and
nights. Shift work outside of 6am-6pm has been reported to cause fatigue, induce sleep
disorders, and cause metabolic disturbances. This shift to a nocturnal 'day' rather than
diurnal, can result in reduced work performance, processing errors, accidents at work,
absenteeism, and reduced quality of life. More chronically, those working at night have been
shown to experience higher risks of heart disease, cancer and shorter median durations of
life span. Much of this elevated risk is thought to be due to altered exposure to light, the
dominant environmental cue regulating our circadian rhythms.
As diurnal organisms much of our biology is regulated by the solar day. Acutely, bright light
exposure (i.e., sun) regulates the phase of the biological clock principally through the
suppression of melatonin, which biologically mediates increased alertness and in essence,
'our daytime alertness'. During the night melatonin gradually increases and induces tiredness
and ultimately sleep. This, in part, is biology behind the use of melatonin in those with
sleep disturbances or to mitigate jet lag, with cross-continental or transoceanic flights.
In this study, the investigators will randomize nurses in the hospital to receive either high
intensity white light (3,000 lux) or standard ambient white fluorescent (~400 lx) light for
10 hours during their night shift. This high illuminance light, rich in blue spectrum, is
what diurnal creatures, like humans, are exposed to during the day. The lights may
subsequently be equipped with blue filters (442 nm) to heighten the exposure to the rich blue
spectrum light. Exposure will commence at the beginning of the night shift (~7pm) and
continue for 10 hours. The rationale for terminating exposure prior to shift end is to foster
an onset of sleep biology. At the end of each shift, the nurses will complete the Stanford
Sleepiness Scale and the Psychomotor Vigilance Task (PVT). Saliva samples will be collected
for melatonin level analysis and the nurses will complete sleep diaries at home. The
investigators hypothesize that exposure to high intensity lighting during night shifts will
reduce fatigue and enhance alertness and computational capacity that correlates with reduced
melatonin.
nights. Shift work outside of 6am-6pm has been reported to cause fatigue, induce sleep
disorders, and cause metabolic disturbances. This shift to a nocturnal 'day' rather than
diurnal, can result in reduced work performance, processing errors, accidents at work,
absenteeism, and reduced quality of life. More chronically, those working at night have been
shown to experience higher risks of heart disease, cancer and shorter median durations of
life span. Much of this elevated risk is thought to be due to altered exposure to light, the
dominant environmental cue regulating our circadian rhythms.
As diurnal organisms much of our biology is regulated by the solar day. Acutely, bright light
exposure (i.e., sun) regulates the phase of the biological clock principally through the
suppression of melatonin, which biologically mediates increased alertness and in essence,
'our daytime alertness'. During the night melatonin gradually increases and induces tiredness
and ultimately sleep. This, in part, is biology behind the use of melatonin in those with
sleep disturbances or to mitigate jet lag, with cross-continental or transoceanic flights.
In this study, the investigators will randomize nurses in the hospital to receive either high
intensity white light (3,000 lux) or standard ambient white fluorescent (~400 lx) light for
10 hours during their night shift. This high illuminance light, rich in blue spectrum, is
what diurnal creatures, like humans, are exposed to during the day. The lights may
subsequently be equipped with blue filters (442 nm) to heighten the exposure to the rich blue
spectrum light. Exposure will commence at the beginning of the night shift (~7pm) and
continue for 10 hours. The rationale for terminating exposure prior to shift end is to foster
an onset of sleep biology. At the end of each shift, the nurses will complete the Stanford
Sleepiness Scale and the Psychomotor Vigilance Task (PVT). Saliva samples will be collected
for melatonin level analysis and the nurses will complete sleep diaries at home. The
investigators hypothesize that exposure to high intensity lighting during night shifts will
reduce fatigue and enhance alertness and computational capacity that correlates with reduced
melatonin.
This is randomized crossover trial, in which each nursing subject will serve as his or her
own control: i.e., matched. The subjects will be nurses from the 6FG Trauma Intensive Care
Unit at UPMC Presbyterian hospital. The PI or co-investigator will approach each nurse prior
to the initiation of this study to obtain informed consent. Each nurse subject works
approximately 7-8 nights out of 18 shifts in each month. The duration of this study is 1
month.
Each subject will be exposed to either the intervention or control arm solely based upon
nursing assignment. Currently, nurses are assigned to care for patient on either the F or G
side of the 6FG ICU, and there will be no changes made to shift assignments. For the purposes
of this study, the F wing of the ICU will be ambient, standard white fluorescent
environmental light and serve as control. The G wing of the ICU will be equipped with high
illuminance white lights positioned throughout the hallway to generate a uniform exposure of
approximately 3,000 lux. The current evidence suggests that >2000 lux is needed to achieve
biological effects. The lights used are identical to those commercially available for the
treatment of seasonal affective disorder. There have been over 70 clinical trials and several
meta-analyses that have demonstrated the efficacy of light therapy for SAD. Adverse events
were not significantly different between the light therapy and control groups. Thus, nurses
will be assigned to either intervention or control based upon their standard nursing
assignments.
At the end of each shift, subjects will complete the Stanford Sleepiness Scale on paper. This
is the gold standard for subjective sleepiness levels. It was developed by Hoddes et al
(1973) and is a simple 7-point rating scale. The scale is well validated and has been used in
over 100 clinical trials. In addition, they will next complete the Psychomotor Vigilance Task
(PVT) on their computer in the ICU. This test is the standard objective measure of alertness
and wakefulness. It has been employed as a marker of attention deficit in hundreds of studies
to date. It is a 10 minute test in which the subjects look at a small rectangular screen and
press the mouse every time a bright circle appears. The number of lapses (responses greater
than 500 ms) is recorded. Subjects will be assessed a total of n=6 times during the period of
study.
The quality of sleep the day following exposure to either intervention or control will be
assessed through the use of a sleep diary. The Consensus Sleep Diary was developed in 2012 by
a collaboration of insomnia experts. The subject will record what time they got into bed,
time they went to sleep, how long to fall asleep, how many times they woke up, time they
finally woke up, time they got out of bed, rate the quality of sleep, and how rested or
refreshed they felt. Subjects will maintain 1 diary that will catalogue sleep during a total
of n=6 night shifts.
The principle biologic mediator of sleep and wakefulness is melatonin. Saliva samples will be
collected at the start of the shift (around 7pm) and at the end of the shift (around 7am).
Samples will be stored at -80 degrees for future analysis. Nurses will be sampled a total of
n=2 times. These samples will be stored for a maximum of 1 month. At the conclusion of the
period of study and collection of all samples, which is estimated to be 1 month, all samples
will be analyzed. No sample with be stored after analysis.
The subjects will complete the Stanford Sleepiness Scale on paper at the end of each shift.
This is the gold standard for subjective sleepiness levels. It was developed by Hoddes et al
(1973) and is a simple 7-point rating scale. The scale is well validated and has been used in
over 100 clinical trials. In addition, they will next complete the Psychomotor Vigilance Task
(PVT) on their computer in the ICU. This test is the standard objective measure of alertness
and wakefulness. It has been employed as a marker of attention deficit in hundreds of studies
to date. It is a 10 minute test in which the subjects look at a small rectangular screen and
press the mouse every time a bright circle appears. The number of lapses (responses greater
than 500 ms) is recorded.
The quality of sleep the day following exposure to either intervention or control will be
assessed through the use of a sleep diary. The Consensus Sleep Diary was developed in 2012 by
a collaboration of insomnia experts. The subject will record what time they got into bed,
time they went to sleep, how long to fall asleep, how many times they woke up, time they
finally woke up, time they got out of bed, rate the quality of sleep, and how rested or
refreshed they felt.
The principle biologic mediator of sleep and wakefulness is melatonin. Saliva samples will be
collected at the start of the shift (around 7pm), at 3am (normal melatonin peak time), and at
the end of the shift (around 6am). Samples will be stored at -80 degrees for future analysis.
own control: i.e., matched. The subjects will be nurses from the 6FG Trauma Intensive Care
Unit at UPMC Presbyterian hospital. The PI or co-investigator will approach each nurse prior
to the initiation of this study to obtain informed consent. Each nurse subject works
approximately 7-8 nights out of 18 shifts in each month. The duration of this study is 1
month.
Each subject will be exposed to either the intervention or control arm solely based upon
nursing assignment. Currently, nurses are assigned to care for patient on either the F or G
side of the 6FG ICU, and there will be no changes made to shift assignments. For the purposes
of this study, the F wing of the ICU will be ambient, standard white fluorescent
environmental light and serve as control. The G wing of the ICU will be equipped with high
illuminance white lights positioned throughout the hallway to generate a uniform exposure of
approximately 3,000 lux. The current evidence suggests that >2000 lux is needed to achieve
biological effects. The lights used are identical to those commercially available for the
treatment of seasonal affective disorder. There have been over 70 clinical trials and several
meta-analyses that have demonstrated the efficacy of light therapy for SAD. Adverse events
were not significantly different between the light therapy and control groups. Thus, nurses
will be assigned to either intervention or control based upon their standard nursing
assignments.
At the end of each shift, subjects will complete the Stanford Sleepiness Scale on paper. This
is the gold standard for subjective sleepiness levels. It was developed by Hoddes et al
(1973) and is a simple 7-point rating scale. The scale is well validated and has been used in
over 100 clinical trials. In addition, they will next complete the Psychomotor Vigilance Task
(PVT) on their computer in the ICU. This test is the standard objective measure of alertness
and wakefulness. It has been employed as a marker of attention deficit in hundreds of studies
to date. It is a 10 minute test in which the subjects look at a small rectangular screen and
press the mouse every time a bright circle appears. The number of lapses (responses greater
than 500 ms) is recorded. Subjects will be assessed a total of n=6 times during the period of
study.
The quality of sleep the day following exposure to either intervention or control will be
assessed through the use of a sleep diary. The Consensus Sleep Diary was developed in 2012 by
a collaboration of insomnia experts. The subject will record what time they got into bed,
time they went to sleep, how long to fall asleep, how many times they woke up, time they
finally woke up, time they got out of bed, rate the quality of sleep, and how rested or
refreshed they felt. Subjects will maintain 1 diary that will catalogue sleep during a total
of n=6 night shifts.
The principle biologic mediator of sleep and wakefulness is melatonin. Saliva samples will be
collected at the start of the shift (around 7pm) and at the end of the shift (around 7am).
Samples will be stored at -80 degrees for future analysis. Nurses will be sampled a total of
n=2 times. These samples will be stored for a maximum of 1 month. At the conclusion of the
period of study and collection of all samples, which is estimated to be 1 month, all samples
will be analyzed. No sample with be stored after analysis.
The subjects will complete the Stanford Sleepiness Scale on paper at the end of each shift.
This is the gold standard for subjective sleepiness levels. It was developed by Hoddes et al
(1973) and is a simple 7-point rating scale. The scale is well validated and has been used in
over 100 clinical trials. In addition, they will next complete the Psychomotor Vigilance Task
(PVT) on their computer in the ICU. This test is the standard objective measure of alertness
and wakefulness. It has been employed as a marker of attention deficit in hundreds of studies
to date. It is a 10 minute test in which the subjects look at a small rectangular screen and
press the mouse every time a bright circle appears. The number of lapses (responses greater
than 500 ms) is recorded.
The quality of sleep the day following exposure to either intervention or control will be
assessed through the use of a sleep diary. The Consensus Sleep Diary was developed in 2012 by
a collaboration of insomnia experts. The subject will record what time they got into bed,
time they went to sleep, how long to fall asleep, how many times they woke up, time they
finally woke up, time they got out of bed, rate the quality of sleep, and how rested or
refreshed they felt.
The principle biologic mediator of sleep and wakefulness is melatonin. Saliva samples will be
collected at the start of the shift (around 7pm), at 3am (normal melatonin peak time), and at
the end of the shift (around 6am). Samples will be stored at -80 degrees for future analysis.
Inclusion Criteria:
- All ICU nurses working at the University of Pittsburgh Trauma ICU.
Exclusion Criteria:
- Not working nights
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