Sleep

■ TL;DR — The Short Answer Poor sleep lowers testosterone, and TRT can change how you sleep. One week of ~5-hour nights cuts daytime testosterone by 10-15%. Untreated sleep apnea is both a major cause of low T and a condition the Endocrine Society says to treat before starting TRT. Most men on TRT sleep better by months 2-3, though temporary insomnia in the first few weeks is common and usually resolves with morning injections and split dosing. Testosterone and sleep run in both directions: poor sleep lowers testosterone, and testosterone therapy can change how you sleep. Most of your daily testosterone is produced during sleep, and chronic short sleep can cut levels by 10-15% — while untreated sleep apnea is both a major cause of low T and a condition the Endocrine Society says should be treated before starting TRT. Here’s how the relationship works, what to expect in your first month, and when to get a sleep study first.