Understanding Sleep
Neurobiology of Sleep
The hypothalamus has been extensively implicated in the regulation of sleep. In order to achieve this, regions of the hypothalamus interact with the neurones in various other regions of the brain via neurotransmitters to promote sleep or wakefulness over a 24-hour cycle.
Brain regions involved in sleep
In the 1930s, autopsies of patients experiencing excess sleepiness revealed lesions of the posterior hypothalamus, and those of patients with insomnia showed lesions near the anterior hypothalamus in the region of the ventrolateral preoptic nucleus (VLPO) (see Figure 1). This led to the hypothesis that regions in the posterior and anterior hypothalamus had opposing influences – arousal-promoting or sleep-promoting, respectively – on the sleep–wake cycle.1 [Note that the SCN is an arousal-promoting centre, but is located in the anterior hypothalamus].
The major brain regions involved in the coordination of the sleep–wake cycle are:
- arousal-promoting regions of the brain
- suprachiasmatic nucleus (SCN)
- lateral hypothalamus (LH)
- tuberomammillary nucleus (TMN)
- sleep-promoting regions of the brain
- ventrolateral preoptic nucleus (VLPO)
- pineal gland
- brain stem.
References:
1. Norman WM, Hayward LF. The neurobiology of sleep. In: Carney PR, Berry RB, Geyer JD, eds. Clinical Sleep Disorders.© Lippincott Williams & Wilkins, Philadelphia, USA, 2005: 38–55.