Unisom vs Melatonin: Which Is Better for Sleep? (2026)

Quick Answer: Unisom SleepTabs (doxylamine 25 mg) is an FDA-regulated OTC drug that sedates you by blocking histamine; it’s labeled for occasional sleeplessness in people 12+, but it often causes next-day grogginess and is on the list of drugs older adults should avoid. Melatonin is a hormone that signals “night” to your body clock; it’s sold as a dietary supplement, works best for jet lag and shifting your sleep timing, has small effects on general insomnia, and usually causes fewer next-day effects at low doses (0.5–3 mg). Note that some Unisom products (SleepGels) are diphenhydramine, and Unisom also sells melatonin products, so check the label. For insomnia lasting weeks, neither is the recommended treatment; CBT-I is.

Unisom vs Melatonin at a Glance

Feature	Unisom SleepTabs	Melatonin
What it is	OTC drug: doxylamine succinate 25 mg	Dietary supplement (hormone); not FDA-approved for sleep in the U.S.
How it works	Blocks brain histamine (H1) → sedation	Signals darkness to the circadian clock; mild sleep-promoting effect
Best evidence for	Occasional trouble falling asleep	Jet lag, delayed sleep phase, some shift-work and certain pediatric conditions (with a doctor)
Dose	1 tablet 30 min before bed, 12+	Studies commonly use 0.5–5 mg; low doses often enough
Next-day effects	Grogginess common (long-acting)	Usually mild at low doses; headache, dizziness, drowsiness possible
Older adults	Avoid (Beers Criteria)	Generally better tolerated; ask your doctor
Children	Do not use under 12	Only with pediatrician guidance; overdose reports rising
Quality control	FDA-regulated drug manufacturing	Supplement; tested products often differ from label
Pregnancy	Ask a health professional	Ask a health professional; limited data

Doses above are from the current U.S. Drug Facts or prescribing labels listed in Sources. Always follow the label on the package you buy, because store brands and formulations differ.

Sedation vs Timing

Doxylamine is a first-generation antihistamine. Blocking histamine in the brain makes you drowsy regardless of the time of day, and its anticholinergic effects cause dry mouth, constipation and urinary retention. Melatonin is made by the pineal gland when it gets dark. Taking it in the evening nudges your internal clock and has a modest sleep-promoting effect; it isn’t a strong sedative. That’s why melatonin shines for timing problems and Unisom for simply feeling sleepy.

What the Evidence Shows

Melatonin: NCCIH summarizes that melatonin may help with jet lag and with delayed sleep-wake phase disorder, and may help people fall asleep a little faster, with small effects for general insomnia. Meta-analyses report sleep onset improving by roughly several minutes on average.
Doxylamine: Few modern trials. The AASM guideline on chronic insomnia did not recommend OTC antihistamines (it specifically suggests against diphenhydramine) because benefits were small relative to harms.
Both: The AASM guideline also suggests against melatonin for chronic insomnia in adults, reflecting weak evidence. CBT-I is first-line.

Dosing Tips

Unisom SleepTabs: one 25 mg tablet 30 minutes before bed, only when you have time for a full night’s sleep, no more than once daily. Melatonin: low doses such as 0.5–1 mg taken 1–2 hours before your target bedtime are often as effective as larger doses for timing; for jet lag, take it at the destination’s bedtime for a few nights. Store shelves are dominated by 5–10 mg products, which are more likely to cause grogginess. See our melatonin dose comparison.

Safety

Unisom

Next-morning impairment; the label says don’t drive or operate machinery.
Avoid in adults 65+ (Beers Criteria), and ask a doctor first with glaucoma, an enlarged prostate, asthma or COPD.
Don’t combine with alcohol, other sedatives, NyQuil (also doxylamine) or other antihistamines.

Melatonin

Common side effects are headache, dizziness, nausea and daytime sleepiness.
Supplement quality varies: a study of Canadian products found melatonin content ranged from 83% less to 478% more than labeled, and a 2023 JAMA study of U.S. gummies found most were mislabeled.
Children: CDC data show pediatric melatonin ingestions reported to poison centers rose sharply over the past decade. Keep it locked away, and use only with pediatrician advice.
May interact with blood thinners, seizure medicines, blood pressure and diabetes drugs, and immunosuppressants. Ask a pharmacist.

Can You Take Unisom and Melatonin Together?

There’s no well-known dangerous interaction, but combining sedating products increases next-day drowsiness and isn’t well studied. Most people should choose one. If you’re reaching for both, that’s a sign to talk to a clinician about the cause of your sleep problem.

Pregnancy: A Special Case for Doxylamine

Doxylamine, the antihistamine in Unisom SleepTabs, combined with vitamin B6 (pyridoxine) is FDA-approved as a prescription treatment for nausea and vomiting of pregnancy (brand names Diclegis and Bonjesta), and ACOG lists doxylamine plus B6 as a first-line option for that use. That is a nausea indication with a specific dosing schedule, not a sleep recommendation; anyone pregnant should ask their obstetric clinician before using any sleep aid. For melatonin, NCCIH notes there is little safety information for pregnancy and breastfeeding.

Jet Lag and Shift Work

Melatonin’s strongest use is resetting the body clock rather than knocking you out. NCCIH summarizes evidence that melatonin may help with jet lag and with delayed sleep-wake phase disorder, and that evidence for general insomnia is weaker. Timing matters more than dose: small doses taken a few hours before your desired bedtime in the new time zone shift the clock, while a large dose at the wrong time can leave you groggy. Doxylamine does nothing for circadian timing and can cause next-morning drowsiness after a short night, which matters if you need to drive.

Older Adults

The American Geriatrics Society Beers Criteria advise avoiding first-generation antihistamines such as doxylamine and diphenhydramine in older adults because of confusion, constipation, urinary retention and fall risk. For people over 65, melatonin or, better, non-drug approaches are generally preferred; talk to a clinician about persistent insomnia.

Who Should Choose What

Jet lag or night owl trying to shift earlier: low-dose melatonin.
One-off night when you can’t fall asleep and can sleep 8 hours: Unisom is an option for adults under 65.
65 or older: avoid Unisom; ask your doctor about melatonin or non-drug options.
Trouble most nights for weeks: skip both and ask about CBT-I and screening for sleep apnea, depression or restless legs.

Also comparing: Unisom vs ZzzQuil, melatonin vs magnesium and Advil PM vs Tylenol PM.

When to Talk to Your Doctor or Pharmacist

Sleeplessness lasts more than 2 weeks (the Unisom label says to ask a doctor).
Loud snoring, gasping or pauses in breathing, or unrefreshing sleep despite enough hours.
You’re 65+, pregnant or breastfeeding, or take blood thinners, seizure, blood pressure or diabetes medicines.
Considering melatonin for a child.
Low mood, anxiety or restless legs that keep you awake.

Frequently Asked Questions

Is melatonin safer than Unisom?

For most adults, low-dose melatonin causes fewer next-day effects and fewer anticholinergic side effects than Unisom (doxylamine), and it is not on the Beers list for older adults. But melatonin supplements vary in quality and can interact with some medicines.

Which works better for sleep, Unisom or melatonin?

Unisom is more directly sedating for an occasional sleepless night. Melatonin works best for timing problems such as jet lag or a delayed sleep schedule, and its effect on general insomnia is small.

Can I take Unisom and melatonin together?

There is no well-known dangerous interaction, but combining them increases next-day drowsiness and hasn’t been well studied. Most people should choose one and talk to a clinician if neither helps.

How much melatonin should I take?

Studies commonly use 0.5 to 5 mg, and low doses of 0.5 to 1 mg taken 1 to 2 hours before bedtime are often enough. Higher doses are more likely to cause grogginess.

Is Unisom safe to take every night?

No. It is labeled for occasional sleeplessness, and the label says to see a doctor if sleeplessness lasts more than 2 weeks. Nightly use leads to tolerance and anticholinergic side effects.

Can kids take melatonin or Unisom?

Unisom SleepTabs should not be used under age 12. Melatonin should be used in children only with a pediatrician’s guidance; poison center reports of pediatric melatonin ingestions have risen sharply.

Sources

Medical disclaimer: This article is for educational purposes and does not replace medical advice. Consult a licensed healthcare provider before starting any supplement, medication, or treatment — particularly if you are pregnant, breastfeeding, taking other medications, or have a diagnosed medical condition.