Beullens J
Faculteit Geneeskunde, Katholieke Universiteit Leuven.
Tijdschr Gerontol Geriatr. 1995 Dec;26(6):264-9.
In dementia short nocturnal sleep length, agitation and naps in the day-time suggest a chronobiological disturbance. Bright light therapy seems indicated because of its chronobiological activity. However, dementia is accompanied by a decrease in volume and number of active cells of the suprachiasmatical nuclei, the internal clock. Is the circadian system still functioning then or is it irrevocably damaged? The findings concerning the circadian rhythm of several physiological functions are not consistent but do not show a weakened rhythm. Rest/activity and sleep/wake rhythms, however, are weaker in demented elderly than in their peers. All things considered the internal clock is still functioning and the Zeitgeber maintain their chronobiological activity. Research shows that bright light therapy can restore the sleep/wake rhythm in dementia but research does not uncover the working mechanism. Further studies can give clues for alternative treatments. If the effect of light therapy is based on its Zeitgeber function, other Zeitgeber may be considered as treatments. There is some evidence that an increase in social contacts is effective. The efficiency of light therapy can also be caused by stimulation in a situation of sensory deprivation. There are only anecdotical indications that this stimulus role can also be fulfilled by music.
在痴呆症中，夜间睡眠时间短、烦躁不安以及白天打盹表明存在生物钟紊乱。鉴于其生物钟活性，似乎有必要进行强光疗法。然而，痴呆症伴随着视交叉上核（即内部时钟）活性细胞的数量和体积减少。那么昼夜节律系统仍在发挥作用，还是已不可逆转地受损？关于几种生理功能昼夜节律的研究结果并不一致，但并未显示出节律减弱。然而，痴呆老年人的休息/活动和睡眠/觉醒节律比同龄人更弱。综合考虑，内部时钟仍在发挥作用，且时间信号保持其生物钟活性。研究表明，强光疗法可恢复痴呆症患者的睡眠/觉醒节律，但研究并未揭示其作用机制。进一步的研究可为替代治疗提供线索。如果光疗法的效果基于其时间信号功能，那么可考虑其他时间信号作为治疗方法。有证据表明增加社交接触是有效的。光疗法的效果也可能是由感觉剥夺状态下的刺激引起的。仅有轶事表明音乐也能起到这种刺激作用。
