What does HS (Hour of Sleep) mean for medication timing?

What Does "HS" Mean for Medication Timing?

"HS" is a medical abbreviation that stands for "hour of sleep" (from the Latin "hora somni"), indicating that a medication should be taken at bedtime. 1

Clinical Usage and Context

• The abbreviation "hs" appears consistently in clinical guidelines and prescribing information to denote bedtime dosing. 1

• In medication tables from major cardiology guidelines, "hs" is used interchangeably with "at bedtime" to specify timing for drugs like:

  • Hypnotics and sedatives (eszopiclone 2-3 mg hs, zolpidem 10 mg hs, temazepam 15-30 mg hs) 1
  • Cardiovascular medications requiring once-daily evening dosing 1

Practical Considerations for "HS" Dosing

• Medications prescribed "hs" should be taken immediately before getting into bed for sleep, not simply "in the evening" or "after dinner." 1

• For hypnotic medications specifically, the American Academy of Sleep Medicine emphasizes that "hs" dosing requires allowing appropriate sleep time (typically 7-8 hours) to avoid residual morning sedation. 1

• Administration on an empty stomach is advised for many "hs" medications (particularly hypnotics) to maximize effectiveness, though this should be verified for each specific drug. 1

Important Safety Notes

• The "hs" designation is critical for drugs where timing affects efficacy or safety, such as sleep medications that require adequate sleep opportunity or cardiovascular drugs with specific chronotherapeutic benefits. 1

• Patients should be counseled that "hs" means bedtime specifically, not just nighttime, to ensure proper medication timing and avoid confusion with other evening activities. 1