A hormone responsible for normal sleep wake cycle is

Options

A. epinephrine
B. gastrin
C. melatonin.
D. insulin.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a hormone that regulates the normal sleep-wake cycle.

2. **Analyzing the Options**: The options provided are:
- Epinephrine
- Gastrin
- Melatonin
- Insulin

3. **Evaluating Each Option**:
- **Epinephrine**: This hormone is produced by the adrenal glands and is involved in the body's fight-or-flight response, preparing the body for emergencies. It does not regulate sleep.
- **Gastrin**: This hormone is produced in the stomach and is involved in the digestive process. It does not play a role in the sleep-wake cycle.
- **Melatonin**: This hormone is secreted by the pineal gland and is crucial for regulating the sleep-wake cycle. It helps synchronize the body’s internal clock with the day-night rhythm.
- **Insulin**: This hormone is produced by the pancreas and regulates blood glucose levels. It is not involved in sleep regulation.

4. **Identifying the Correct Answer**: Based on the analysis, melatonin is the hormone that is responsible for the normal sleep-wake cycle.

5. **Final Answer**: The hormone responsible for the normal sleep-wake cycle is **melatonin**.

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