Sleep shapes appetite, food intake, insulin sensitivity, and metabolic health. Learn how to address disruptions, establish a circadian routine, and evaluate CBT-I, supplements, and prescription options.
Introduction
Sleep affects more than how you feel the next morning. It shapes appetite, food intake, insulin sensitivity, and the routines that make metabolic health possible. For most adults, a useful goal is seven to nine hours a night, with a reasonably consistent wake time.
In a prospective study of 1,992 adults (https://pubmed.ncbi.nlm.nih.gov/32138974/), people whose sleep duration varied by more than two hours from night to night had roughly twice the rate of cardiovascular events as those whose sleep varied by no more than one hour. A meta-analysis of prospective studies (https://pubmed.ncbi.nlm.nih.gov/25715415/) found the lowest observed risk of type 2 diabetes at seven to eight hours of sleep. In a six-week randomized crossover trial in women (https://pubmed.ncbi.nlm.nih.gov/37955852/), shortening sleep by about 90 minutes a night impaired insulin sensitivity even without a change in body fat. The first two findings are associations; the trial measured a direct short-term effect of sleep restriction.
Why a short night changes food intake
In a controlled experiment in 12 young men (https://pubmed.ncbi.nlm.nih.gov/15583226/), two nights with four hours in bed, compared with two nights with ten hours in bed, lowered leptin by 18%, raised ghrelin by 28%, and increased reported hunger by 24%. Leptin helps signal fullness; ghrelin promotes hunger. This helps explain why a short night can make the next day’s food decisions feel harder.
The effect on eating is not reducible to one hormone alone. In an eight-night randomized trial (https://pubmed.ncbi.nlm.nih.gov/23392199/), the sleep-restricted group ate a net 677 more calories per day than controls, although leptin and ghrelin did not change significantly in that experiment.
The reverse experiment is useful, too. In a randomized trial of 80 adults with overweight who habitually slept less than 6.5 hours (https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2788694), individualized sleep counseling increased sleep by about 1.2 hours per night over two weeks. Participants ate 270 fewer calories per day than controls without being assigned a diet. A separate six-week randomized trial (https://pubmed.ncbi.nlm.nih.gov/41564347/) found that extending sleep in adults with overweight or obesity improved sleep health but did not improve measured insulin sensitivity. These studies support addressing short sleep; they do not promise diabetes remission from sleep extension.
If you are chronically short on sleep, extending it may help with appetite and food intake. If you have insomnia, spending more time in bed alone is unlikely to solve it. Start by looking at what is disrupting sleep.
Look for what is disrupting sleep
Tell us if you snore loudly, wake gasping, or feel sleepy while driving. Uncomfortable legs that improve when you move can also interfere with sleep. Pain, reflux, frequent urination, hot flashes, mood symptoms, and medications may be part of the picture. These problems deserve clinical assessment while you work on your routine; a supplement will not correct an untreated sleep disorder.
If CPAP comes up during a clinical discussion, see our two-minute conversation with Dr. Alan Schaffer about a nasal-cushion mask.
Build a day that supports the night
Anchor the morning: Wake at about the same time each day, including after a poor night, and get outdoor light soon after waking. If you need a nap, make it brief and early. A consistent wake time is part of the treatment tested in a randomized CBT-I trial (https://pubmed.ncbi.nlm.nih.gov/30481333/); a separate light-treatment trial (https://pubmed.ncbi.nlm.nih.gov/29680419/) studied timed morning light for delayed sleep timing.
Create space after dinner and hard exercise: Our practice target is to finish dinner and vigorous exercise at least five hours before bedtime when feasible. Gentle evening walking or stretching is fine; do not skip food you need to prevent hypoglycemia. An analysis of 14,689 physically active WHOOP users and more than four million nights (https://pubmed.ncbi.nlm.nih.gov/40234380/) found that exercise ending at least four hours before sleep was not associated with sleep disruption. In a separate randomized crossover study of 845 adults (https://pubmed.ncbi.nlm.nih.gov/35015083/), a glucose challenge one hour rather than four hours before bed worsened glucose tolerance. Neither study tested a required five-hour cutoff for insomnia.
Dim the evening: During the last two to three hours before bed, turn off bright overhead lighting and put your phone away. Use low-intensity red light if you need to move around, and keep the room dark for sleep. In a red-versus-blue light experiment (https://pubmed.ncbi.nlm.nih.gov/40430143/), red light suppressed melatonin less than blue light after two hours, although both initially suppressed it. Red light should still be dim.
Reduce other sleep disruptors: Stop caffeine at least eight hours before bed, earlier if you are sensitive or have a large dose. In a dose-and-timing trial (https://pubmed.ncbi.nlm.nih.gov/39377163/), 400 mg of caffeine impaired sleep even when taken within 12 hours of bedtime. Avoid using alcohol to induce sleep. Give yourself 30 to 60 minutes to wind down; a warm shower or bath one to two hours before bed is another option supported by a bathing and sleep analysis (https://pubmed.ncbi.nlm.nih.gov/31102877/).
Make the bedroom easy to sleep in: Blackout curtains, a comfortably cool room, and steady background noise may help. A HEPA filter can help if allergies interrupt your nights. A weighted blanket is an option if it feels comfortable and is easy to remove; a 120-person randomized trial (https://pubmed.ncbi.nlm.nih.gov/32536366/) found improved insomnia ratings in people with psychiatric conditions. Room changes support comfort but do not replace treatment for chronic insomnia.
What to do when you cannot sleep
Go to bed when you feel sleepy. If you are lying awake and becoming frustrated, get out of bed and read a dull book or do something quiet under dim light. Return when you feel sleepy, and repeat if needed. Keep the bed for sleep and sex. This is stimulus control: it helps break the learned connection between bed and wakeful frustration. It was included in the CBT-I tested in a randomized trial of 150 postmenopausal women (https://pubmed.ncbi.nlm.nih.gov/30481333/).
Persistent insomnia calls for a treatment plan
If sleeplessness continues, ask about cognitive behavioral therapy for insomnia (CBT-I). It combines stimulus control with a consistent wake time, relaxation, work on sleep-related thoughts, and a sleep window adjusted with a diary. In a randomized trial of 150 postmenopausal women (https://pubmed.ncbi.nlm.nih.gov/30481333/), CBT-I produced higher insomnia-remission rates than sleep-hygiene education alone. In a randomized trial of 303 adults (https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2589161), 56.6% of those assigned to digital CBT-I and assessed at one year met remission criteria. CBT-I can begin while you work on your routine or supplements; you do not need to wait for them to fail.
Keep a two-week sleep diary: record bedtime, estimated sleep time, awakenings, wake time, naps, caffeine, dinner, exercise, and supplements. We can also track an Insomnia Severity Index (ISI) score at the start and again after four to eight weeks; both tools were used in a randomized CBT-I trial (https://pubmed.ncbi.nlm.nih.gov/30481333/). Do not set an aggressive sleep-restriction schedule on your own, particularly if you have bipolar disorder, seizures, marked daytime sleepiness, or safety-sensitive work.
Supplements before prescription medication
Alongside the sleep routine and CBT-I when indicated, our initial supplement approach is magnesium glycinate and glycine. L-theanine, ashwagandha, and GABA are additional individual options. If sleep has not improved after three weeks, consider one of the blends below after reviewing its ingredients with us. Add one new product at a time so you can tell what helps.
- Magnesium glycinate: Check the label for elemental magnesium. Start with 100 mg in the evening for one week. If sleep has not improved and stools remain normal, increase to 200 mg nightly for the next week. If needed and tolerated, increase to 250 to 300 mg nightly; stop increasing when you find a helpful dose. If stools become newly soft or watery, or you develop cramping, stop magnesium and let us know. Unless your clinician directs otherwise, keep magnesium from all supplements, antacids, laxatives, and drink mixes at or below 350 mg elemental magnesium per day. Ask before starting if you have kidney disease or take medicines that interact with magnesium. A 2025 randomized trial of 155 adults (https://pubmed.ncbi.nlm.nih.gov/40918053/) found a modest improvement in insomnia scores with 250 mg elemental magnesium daily for four weeks. NIH dietary data (https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/) show that 48% of Americans surveyed had magnesium intake below their estimated requirement; magnesium content also varies widely in drinking water (https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/). A wheat study (https://pubmed.ncbi.nlm.nih.gov/19013359/) found lower mineral density in some modern high-yield varieties.
- Glycine: Take 3 g shortly before bed, the dose used in a human sleep study (https://doi.org/10.1111/j.1479-8425.2007.00262.x).
- L-theanine: Take 200 mg before bed if stress or a busy mind is keeping you up. A four-week randomized crossover trial (https://pubmed.ncbi.nlm.nih.gov/31623400/) used this dose nightly and found improvements in self-reported sleep measures.
- Ashwagandha: Consider 300 mg of standardized root extract twice daily, once in the morning and once in the evening. In a 10-week randomized trial of 60 people with insomnia and anxiety (https://pubmed.ncbi.nlm.nih.gov/31728244/), this dose improved sleep onset and sleep quality compared with placebo. Do not use during pregnancy or breastfeeding. Check with us first if you have thyroid or liver disease or take interacting medicines; see the NIH safety summary (https://www.nccih.nih.gov/health/ashwagandha).
- GABA: Consider 300 mg in the evening. In a four-week randomized trial of 40 people with insomnia symptoms (https://pubmed.ncbi.nlm.nih.gov/29856155/), rice-germ-derived GABA at this daily dose improved sleep latency and sleep efficiency in the treatment group.
Combination product considerations
Choose one packet or powder after reviewing its current label and the magnesium and other calming supplements you already take. The studies above tested individual ingredients and doses, which may differ from the amounts in a finished blend.
Nectar Essential Daily Calm is our preferred sugar-free, melatonin-free packet. Start with one packet after checking its current label with our team. Its ingredient list (https://drinknectar.com/) includes magnesium glycinate, L-theanine, and ashwagandha. Count the packet’s magnesium toward your daily total, and do not automatically add separate L-theanine or ashwagandha on top.
Natural Vitality CALM Sleep powder is a melatonin-containing alternative. Its product label (https://www.naturalvitality.com/products/calm-sleep-with-melatonin-powder-wildberry-6-oz-170-g-powder-nv3952) lists 220 mg magnesium, 50 mg L-theanine, 100 mg GABA, and 5 mg melatonin per serving. Use one label-directed serving and check the combined amounts before adding another magnesium product or blend. We prefer a melatonin-free option when it fits: in an acute crossover study (https://pubmed.ncbi.nlm.nih.gov/25197811/), 5 mg melatonin taken near a glucose challenge worsened glucose tolerance. That study tested an acute metabolic response, not whether this powder causes diabetes.
Matching prescription options when necessary
We generally try to avoid sleep medication unless it is necessary. We first address causes, use CBT-I for persistent insomnia, build a workable routine, and discuss the supplement options above. If insomnia remains burdensome or short-term relief is needed, a prescription may help. We choose according to what is happening at night, check whether it improves daytime function, and revisit benefit and side effects. These options differ for falling asleep and staying asleep.
Trouble falling asleep and staying asleep: An orexin receptor antagonist such as daridorexant or lemborexant. Two three-month daridorexant trials (https://pubmed.ncbi.nlm.nih.gov/35065036/) found better sleep onset and maintenance with 25 to 50 mg; 50 mg also improved a daytime-function measure. A 1,006-person trial in adults 55 and older (https://pubmed.ncbi.nlm.nih.gov/31880796/) found better objective sleep measures with lemborexant 5 to 10 mg than with placebo or zolpidem extended release over one month.
Waking during the night or too early: Low-dose doxepin, 3 to 6 mg. In a 35-day randomized trial (https://pubmed.ncbi.nlm.nih.gov/21966075/), both doses reduced time awake after sleep onset and improved sleep in the final part of the night. This is the low-dose insomnia treatment, not an antidepressant-dose regimen.
Mainly trouble falling asleep: Ramelteon, 8 mg. In a 405-person randomized trial (https://pubmed.ncbi.nlm.nih.gov/17803013/), average time to persistent sleep at week one was 32 minutes with 8 mg versus 48 minutes with placebo. It did not significantly reduce nighttime awakenings. Ramelteon acts at melatonin receptors; it is a prescription medicine distinct from a melatonin supplement.
Severe symptoms needing short-term relief: A carefully selected Z-drug such as zolpidem while CBT-I is underway. A 160-person randomized trial (https://pubmed.ncbi.nlm.nih.gov/19454639/) found the best six-month follow-up remission rate when initial CBT-I plus zolpidem was followed by CBT-I without zolpidem, compared with continuing intermittent zolpidem (68% versus 42% in those groups).
Hydroxyzine and trazodone sit lower in this discussion for chronic insomnia. Hydroxyzine’s sleep evidence comes from small studies: a review identified five studies totaling 207 treated patients (https://pubmed.ncbi.nlm.nih.gov/36843057/). In a 306-person trial of trazodone 50 mg, zolpidem, and placebo (https://doi.org/10.1002/%28SICI%291099-1077%28199804%2913%3A3%3C191%3A%3AAID-HUP972%3E3.0.CO%3B2-X), trazodone’s benefit over placebo on sleep latency was no longer significant in week two. Other symptoms or conditions can still affect a prescriber’s choice.
Use any sleep medicine only as prescribed. Do not combine sedating medicines, alcohol, or calming supplements without checking with your prescriber. If zolpidem is prescribed, take it immediately before bed only when seven to eight hours remain for sleep; its prescribing information (https://www.accessdata.fda.gov/drugsatfda_docs/label/2022/019908s40s044s047lbl.pdf) also warns about sleepwalking, sleep-driving, and other activities while not fully awake. If any of those occur, stop it and contact your prescriber promptly. Do not change a regular prescription or taper it on your own.
The complete sleep plan
Better sleep starts with enough time for sleep, a consistent wake time, morning light, an evening that protects darkness and recovery, and a bedroom that supports rest. We look for apnea, pain, restless legs, medication effects, and other causes when the pattern suggests them. If insomnia persists, CBT-I provides a structured way to change the habits and expectations that keep it going. Supplements can be added thoughtfully, with one change at a time; medication is reserved for situations where the expected benefit justifies it.
Track the pattern, not just one bad night. If sleep is not improving after two to four weeks, bring a two-week sleep diary to the team so we can adjust the plan. Tell us sooner if you are sleepy while driving, wake gasping, develop a new reaction to a supplement, or suspect another medical problem is interrupting sleep. The goal is restorative sleep you can sustain, alongside better appetite regulation, metabolic health, and daytime function.
