Sleep Physiology Examination Paper

# **Time: 3 Hours****Total Marks: 80** --- ## SECTION A: MULTIPLE CHOICE QUESTIONS (40 MARKS) *Choose the best answer for each question. Each question carries 1 mark.* ### 1. Which thalamic nucleus is primarily responsible for relaying visual information to the cortex? A) Medial geniculate body B) Lateral geniculate body C) VPL nucleus D) Anterior nucleus **Answer: B) Lateral geniculate body****Explanation:** The lateral geniculate body specifically relays visual information from the retina to the visual cortex, while the medial geniculate body handles auditory information. ### 2. The neurotransmitter primarily released by the locus coeruleus that promotes wakefulness is: A) Serotonin B) GABA C) Norepinephrine D) Acetylcholine **Answer: C) Norepinephrine****Explanation:** The locus coeruleus is the primary source of norepinephrine in the brain and is a key component of the ascending arousal system. ### 3. Sleep spindles are characteristic of which stage of NREM sleep? A) Stage 1 B) Stage 2 C) Stage 3 D) REM sleep **Answer: B) Stage 2****Explanation:** Sleep spindles (10-14 Hz bursts) are the defining feature of Stage 2 NREM sleep, generated by the thalamic reticular nucleus. ### 4. The master circadian pacemaker is located in the: A) Pineal gland B) Suprachiasmatic nucleus C) Locus coeruleus D) Raphe nuclei **Answer: B) Suprachiasmatic nucleus****Explanation:** The SCN receives direct input from the retina via the retinohypothalamic tract and coordinates all circadian rhythms. ### 5. PGO spikes during REM sleep originate from: A) Pons → Geniculate → Occipital cortex B) Parietal → Geniculate → Occipital cortex C) Pons → Globus pallidus → Occipital cortex D) Pineal → Geniculate → Occipital cortex **Answer: A) Pons → Geniculate → Occipital cortex****Explanation:** PGO spikes are generated in the pons and travel through the lateral geniculate nucleus to the occipital cortex, marking REM sleep onset. ### 6. The EEG frequency range for alpha rhythm is: A) 4-7 Hz B) 8-13 Hz C) 13-30 Hz D) 30-100 Hz **Answer: B) 8-13 Hz****Explanation:** Alpha rhythm (8-13 Hz) is seen in awake, resting adults with eyes closed and indicates a relaxed, low-attention state. ### 7. Which neurotransmitter is inhibitory and promotes sleep when released from the preoptic area? A) Glutamate B) Histamine C) GABA D) Orexin **Answer: C) GABA****Explanation:** GABA neurons in the preoptic area of the hypothalamus are sleep-promoting and inhibit arousal systems. ### 8. The approximate duration of a complete sleep cycle is: A) 60 minutes B) 90 minutes C) 120 minutes D) 150 minutes **Answer: B) 90 minutes****Explanation:** Sleep cycles average 90 minutes, with 4-6 cycles occurring during a typical 8-hour sleep period. ### 9. Delta waves are most prominent during: A) REM sleep B) Stage 1 NREM C) Stage 2 NREM D) Stage 3 NREM **Answer: D) Stage 3 NREM****Explanation:** Delta waves (0.5-4 Hz) are the slowest, highest amplitude waves and define Stage 3 NREM (slow-wave sleep). ### 10. Melatonin is synthesized in the: A) Hypothalamus B) Pineal gland C) Thalamus D) Brainstem **Answer: B) Pineal gland****Explanation:** The pineal gland produces melatonin in response to darkness, regulated by the SCN via sympathetic innervation. ### 11. Which of the following is characteristic of REM sleep? A) High muscle tone B) Slow eye movements C) Muscle atonia D) High-amplitude EEG waves **Answer: C) Muscle atonia****Explanation:** REM sleep is characterized by muscle atonia (except respiratory and eye muscles) to prevent acting out dreams. ### 12. The percentage of REM sleep in full-term neonates is approximately: A) 25% B) 50% C) 75% D) 80% **Answer: B) 50%****Explanation:** Full-term neonates spend about 50% of sleep time in REM, which decreases to about 25% in adults. ### 13. Beta rhythm is associated with: A) Deep sleep B) Drowsiness C) Alert wakefulness D) Coma **Answer: C) Alert wakefulness****Explanation:** Beta rhythm (13-30 Hz) appears during focused attention and mental tasks, representing the alert/awake state. ### 14. Orexin neurons are located in the: A) Brainstem B) Thalamus C) Lateral hypothalamus D) Cortex **Answer: C) Lateral hypothalamus****Explanation:** Orexin (hypocretin) neurons in the lateral hypothalamus stabilize sleep-wake transitions and promote wakefulness. ### 15. The EEG in REM sleep shows: A) High-voltage, slow waves B) Sleep spindles C) Low-voltage, fast activity D) Delta waves **Answer: C) Low-voltage, fast activity****Explanation:** REM sleep EEG resembles waking EEG with low-voltage, high-frequency activity, hence "paradoxical sleep." ### 16. Chandelier cells in the cortex: A) Release glutamate B) Target pyramidal cell axon initial segments C) Promote excitation D) Are located in deep cortical layers **Answer: B) Target pyramidal cell axon initial segments****Explanation:*