2.01 Seasonal Affective Disorder and Light Therapy
Light therapy for winter depression (seasonal affective disorder) was first developed and explored about 35 years ago at the US National Institute of Mental Health (NIMH). It was a momentous leap from basic biological thinking, which looked for causes of behavior within living things. Instead, the new focus of attention was on the environment－an emphasis […]
2.10 Circadian Rhythm Influences on Medical Conditions, and Risk Factors
While our literature survey has emphasized circadian factors that affect psychological and sleep disturbances, and non-drug treatment approaches that normalize the daily cycle, there is an explosion of research on medical applications that very possibly will transform how doctors diagnose illness and manage treatment, with less reliance on conventional medication, or with significant dose reduction […]
2.09 Chronotype, Circadian Clock Phase, and Period
Night owl or lark or in-between: everyone operates on a circadian cycle referenced to day and night outdoors. There are two main ways to place an individual on this dimension: physiological and behavioral. Physiological specification of early, middle, or late types can be made by taking samples of saliva throughout the evening, up through bedtime, […]
2.08 Chronotherapeutics: Light and Wake Therapy
A remarkable observation in the 1970’s—inspired by a depressed bipolar patient who stayed awake bike riding all night—was the immediate relief of deep depression after a night without sleep (then called “sleep deprivation”). Such a virtually instantaneous remission had never before been seen in psychiatry. It could not be adopted clinically because partial or complete […]
2.07 Prospects for New Applications of Light Therapy
We are far from knowing the limits of light therapy, or the involvement of circadian timing in mental and physical illness. New exploratory applications give a sense of the broad range of possibilities, although the research needs extensive follow-up before we endorse or codify the intervention as a mainline strategy, or alternative to established medication […]
2.06 Circadian Analysis of Shift Work Disorder, and Treatment Approaches
Shift workers are required to be awake and alert, often at times when the circadian clock is in its incompatible nighttime mode. The ensuing lack of alertness can spell danger—on the road, operating machinery, prescribing medications in the emergency room, and so on. Some people are more tolerant to shift work than others. A night […]
2.05 Circadian Analysis of Jet Lag, and Treatment Approaches
When we take a flight across time zones, our circadian timing system has no knowledge of the shift to a new light-dark cycle, so it stays at home base, and adjusts only gradually. On landing, the inner clock may be set to night, even if it is midday outdoors. The conflict produces jet lag, with […]
2.04 Circadian Properties of Melatonin and Its Relationship to Sleep
The hormone melatonin, produced by the pineal gland, is a sleep facilitator with circadian action. In the normal case, the inner clock in the suprachiasmatic nuclei (SCN) sends an “on” signal to the pineal gland sometime in the evening a couple of hours before we feel ready for sleep, and an “off” signal shortly before […]
2.03 Circadian Rhythm Sleep Disorders and Their Treatment
No one will be surprised that our sleep-wake cycle is closely related to the circadian timing system. This first became obvious in time-isolation studies where subjects could go to sleep and rise as they wished, but without a clock on the wall to guide or remind them. Their sleep-wake cycle followed a free-running circadian pattern, […]
2.02 Later Demonstrations of Light Therapy for Psychiatric Disorders
Given the success and rapid spread of light therapy for SAD, clinical researchers immediately wondered how far the simple technology could be applied. Multiple studies—although performed on a smaller scale than for SAD—covered a wide canvas, almost all with encouraging results. Light therapy also worked for nonseasonal depression, even unremitting chronic depression that didn’t lift […]