Sleep is essential for regulating mood, memory, and emotional balance. When you don’t get enough rest, stress hormones remain elevated, making you more irritable, anxious, and prone to negative thinking. Poor sleep can worsen depression and anxiety symptoms and reduce your ability to cope with daily challenges. Improving sleep hygiene — such as maintaining a consistent bedtime, avoiding screens before bed, and creating a relaxing environment — can make a big difference. If sleep problems persist, they may indicate an underlying condition.