Bad things happen. We all experience negative life events, and common sense tells us that mood disorders such as depression are often precipitated by such events. The loss of a job, failing a vital exam, the break-up of a long-term relationship - all of these things rank fairly high in terms of the slings and arrows outrageous misfortune occasionally sends our way. Recent research suggests, however, that these events may have profound effects if they disrupt our social rhythms, most importantly the times - and amount - we eat and sleep. This idea has been termed the "social rhythm disruption hypothesis" and is based on the observation that such disruptions, even in the absence of any psychological threat, can play an important role in the onset of the disordered mood states we label depression and mania.
One recent study explored the social rhythm-disruption hypothesis in patients with manic and depresive episodes. The results showed that manic episodes were particularly associated with events that disrupted social rhythms. Several other studies have provided further experimental support for this idea by employing controlled sleep deprivation. In one such study, 12 depressed bipolar patients were deprived of sleep for one night; nine of these patients developed mania/hypomania either during the night of the deprivation or on the following day, and several remained manic for weeks afterward. This perhaps explains the historical and cultural association of mental illness with the moon.
Consider, for example, the full moon's ability to disturb the sleeping patterns of individuals prior to the advent of modern lighting. So while negative life events and individual psychology and biology are implicated in the onset of mood disorders, it could be sleep disruption that is the final pathway in the onset of manic episodes. This is further supported by clinical observation of common precipitating factors in mania, including amphetamine use, the postpartum period, long-distance travel and withdrawal from alcohol.
All of these stressors are highly likely to be associated with a reduction in the amount sleep individuals get, suggesting that the effects of these factors are at least partially mediated by sleep deprivation. These findings have lead to what clinicians now term choronotherapeutics, or body clock theraputics. More specifically, chronotheraputics involve total and partial sleep deprivation, and have both been used to successful therapeutic ends. Total sleep deprivation and late partial sleep deprivation, collectively referred to as "wake therapy", have been reported to improve symptoms in as many as 60 per cent of people experiencing depressive episodes. Similarly, combinations of pharmacotherapy and partial sleep deprivation have been reported as being more effective than either alone.
However, several other studies that employed wake therapy as an intervention with bipolar depressed patients found that wake therapy can trigger a manic episode. So in the context of bipolar disorder (cases in which people experience intermittent episodes of mania and depression) caution is called for and the use of mood stabilizers in conjunction with sleep deprivation is advised. The research into life events and social dysrhythmia has also led to the development of a therapeutic treatment approach for bipolar disorders inclusive of manic episodes. The Interpersonal and social Rhythm Therapy (IPSRT) approaches an existing psychological intervention method, Interpersonal Psychotherapy, with the sleep rhythm-disruption model. IPSRT assessment includes the social rhythm metric, a tool designed to identify the individual's specific social rhythm-disruption triggers. This enables the individual to monitor mood and social interactions during these periods, with the goal of re-establishing social rhythms, especially when early warning signs of depressive or manic episodes have been identified.
A recent two-year follow-up study assessing the outcomes of individuals receiving IPSRT or intensive case management in the context of bipolar disorder reported that IPRST was associated with superior outcomes, most notably fewer relapses during the two-year period following the therapy. The next time you take a long-haul flight and are feeling giddy, strangely creative and energetic, despite not having slept that much, you may be experiencing the antidepressant but mania-inducing effects of sleep deprivation.
Justin Thomas is professor of psychology in the department of health science at Zayed University in Abu Dhabi
