Task: Categorize the tweet's emotional expression, classifying it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that reflect the tweeter's state of mind.
Tweet: 😩😩😩😩 heads melted, very tired but can't sleep. #nightmare
This tweet contains emotions: 
fear, pessimism