31 Factors • 28 Studies • Updated Apr 2026
The things keeping you up at 3 AM — ranked.
Every nutrition choice, supplement, habit, and environmental variable with measurable impact on staying asleep — sorted by the minutes of wake time it adds or removes from your night. No guessing. Just the data.
31
Factors tracked
11
Help you stay asleep
16
Wake you up
17
Strong-evidence
The evidence
What the evidence actually says.
View 01 / 03
Impact chart
Ranked by magnitude
01
Leaderboard
Every factor, sortable
02
Night timeline
Grouped by time of day
03
Bar length = minutes of Wake After Sleep Onset added or removed per night. Only factors with numeric WASO figures appear in the chart. Tap a bar for the mechanism and source.
All
31
Nutrition & Substances
6
Supplements
6
Exercise & Movement
5
Environment & Hygiene
5
Demographics & Physiology
9
View 02 / 03
All 31 factors, sortable by impact, evidence, direction, or category. Tap a row for the key finding, mechanism, and source link.
All
Sort by
Impact
Evidence
Direction
Category
#
Factor
Direction
Effect
Evidence
WASO Δ
Yoga
↓ Helps
Positive (−56 min WASO, likely inflated)
LIMITED
-56 min
Nocturia (≥2 episodes/night)
↑ Hurts
Negative (+34 min WASO)
STRONG
+34 min
Noise (>50 dBA)
↑ Hurts
Negative (+30 min WASO)
STRONG
+30 min
04
Vigorous Exercise ≤1 hr Pre-Bed
↑ Hurts
Negative (+21.9 min WASO)
MODERATE
+22 min
05
Tart Cherry Juice
↓ Helps
Positive (−17 min WASO)
MODERATE
-17 min
06
Caffeine
↑ Hurts
Negative (+12 min WASO)
STRONG
+12 min
07
Moderate Aerobic Exercise
↓ Helps
Positive (−10 min WASO)
STRONG
-10 min
08
Aging (30–60+)
↑ Hurts
Negative (+10 min WASO/decade)
STRONG
+10 min
09
CO₂ >1000 ppm (Poor Ventilation)
↑ Hurts
Negative (+5 min wake)
MODERATE
+5 min
10
Dietary Fiber
↓ Helps
Positive (↓ arousals)
STRONG
—
11
Sugar / Refined Carbs
↑ Hurts
Negative (↑ arousals)
STRONG
—
12
Alcohol
↑ Hurts
Negative (↑ fragmentation)
STRONG
—
13
Late Eating (<1 hr pre-bed)
↑ Hurts
Negative (2–2.6× WASO odds)
MODERATE
—
14
Melatonin (Immediate-Release)
— Neutral
Null (no WASO effect)
STRONG
±0 min
15
Ashwagandha (600 mg/day)
↓ Helps
Positive (SMD −0.39 for WASO)
STRONG
—
16
Glycine (3 g)
↓ Helps
Positive (↓ WASO, faster SWS)
MODERATE
—
17
Magnesium (500 mg)
↓ Helps
Positive for sleep efficiency
LIMITED
—
18
L-Theanine (200–450 mg)
— Neutral
Mixed WASO results
LIMITED
—
19
Valerian Root
— Neutral
Null (no objective WASO benefit)
WEAK
±0 min
20
Resistance Training
↓ Helps
Positive (↓ disturbance, ↑ efficiency)
MODERATE
—
21
Moderate Evening Exercise
↓ Helps
Positive (↓ WASO)
MODERATE
—
22
Bedroom Temp (20–25°C)
↓ Helps
Positive at optimal range
STRONG
—
23
Light at Night (even dim)
↑ Hurts
Negative (↑ WASO)
STRONG
—
24
Mattress (Medium-Firm)
↓ Helps
Positive (most consistent WASO)
LIMITED
—
25
Female Sex (Subjective–Objective Paradox)
— Neutral
More complaints, better PSG
STRONG
—
26
Menopausal Hot Flashes
↑ Hurts
Negative (69% hot flashes → wake)
STRONG
—
27
Obesity (BMI ≥30)
↑ Hurts
Negative (↑ WASO)
STRONG
—
28
Shift Work
↑ Hurts
Negative (↑ WASO, ↓ efficiency)
MODERATE
—
29
Obstructive Sleep Apnea
↑ Hurts
Negative (↑ WASO, ↑ arousals with severity)
STRONG
—
30
Chronic Pain
↑ Hurts
Negative (large effect)
STRONG
—
Psychological Stress
↑ Hurts
Negative (↑ WASO via cortisol)
MODERATE
—
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View 03 / 03
Factors arranged by when they matter most — from daytime habits, through bedtime rituals, to what is happening in your bedroom overnight.
All
6A–6P
Daytime
Sets the stage — circadian, pressure, cortisol tone.
Caffeine
6–9P
Evening
Wind-down window — the last chance to shape the night.
Sugar / Refined Carbs
9–11P
Bedtime
The hour before lights-out. Highest-leverage window.
Vigorous Exercise ≤1 hr Pre-Bed
11P–6A
Overnight
What's in the room matters more than what's in your head.
Nocturia (≥2 episodes/night)
Always
Chronic / Baseline
Always-on — demographics, disorders, baseline stress.
Aging (30–60+)
The hour before lights-out. Highest-leverage window.
Late Eating (<1 hr pre-bed)
00
What's in the room matters more than what's in your head.
No factors in this slot.
Always
00
Always-on — demographics, disorders, baseline stress.
No factors in this slot.
Free 7-Day Trial
Sets the stage — circadian, pressure, cortisol tone.
No factors in this slot.
6–9P
Wind-down window — the last chance to shape the night.
No factors in this slot.
9–11P
The hour before lights-out. Highest-leverage window.
Melatonin (Immediate-Release)
Always-on — demographics, disorders, baseline stress.
Ashwagandha (600 mg/day)
Sets the stage — circadian, pressure, cortisol tone.
Resistance Training
Wind-down window — the last chance to shape the night.
Moderate Evening Exercise
The hour before lights-out. Highest-leverage window.
No factors in this slot.
11P–6A
What's in the room matters more than what's in your head.
Noise (>50 dBA)
WASO impact per night
Minutes added or removed from Wake After Sleep Onset, per peer-reviewed meta-analysis or RCT.
11 quantified factors
← Helps you stay asleep
Wakes you up →
Yoga
-56 min*
Nocturia (≥2 episodes/night)
+34 min
Noise (>50 dBA)
+30 min
Vigorous Exercise ≤1 hr Pre-Bed
+22 min
Tart Cherry Juice
-17 min
Caffeine
+12 min
Moderate Aerobic Exercise
-10 min
Aging (30–60+)
+10 min
CO₂ >1000 ppm (Poor Ventilation)
+5 min
Melatonin (Immediate-Release)
±0 min
Valerian Root
±0 min
-40
-20
0
+20
+40
*Yoga effect (−56 min) capped at −40 in chart; network meta-analysis rated low-certainty. Chart shows only factors with reported numeric WASO minutes.
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Find what's waking you at 3 AM.
These factors are averages. Kygo correlates your own meals, caffeine and alcohol with the nights you actually sleep through.
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Health
The full breakdown
Every factor, explained.
Browse all 31 by category — direction, evidence grade, mechanism, what to do, and the source. Tap a card to expand.
Nutrition & Substances
6
Helps you stay asleep
2
Dietary Fiber
S
↓ arousals
Read more ↓
Collapse ↑
A tightly controlled inpatient study with polysomnography found higher-fiber days independently predicted fewer sleep arousals. Fiber is one of the strongest dietary signals for staying asleep through the night.
Mechanism. Stable overnight glucose, lower systemic inflammation, and microbiome-driven vagal tone reduce the arousals that fragment deep sleep.
What to do. 25–35 g/day from whole foods
View Dietary Fiber Supplement on Amazon
Tart Cherry Juice
M
−17 min WASO
Read more ↓
Collapse ↑
A small but clean pilot RCT found tart cherry juice cut WASO by about 17 minutes versus placebo in older adults with insomnia. Needs replication at larger scale, but the mechanism is plausible and the signal is direct.
Mechanism. Naturally occurring melatonin and tryptophan plus anti-inflammatory anthocyanins support consolidated overnight sleep.
What to do. 240 mL (8 oz) twice daily; morning and 1–2 hrs pre-bed
View Tart Cherry Juice on Amazon
Wakes you up
4
Sugar / Refined Carbs
S
↑ arousals
Read more ↓
Collapse ↑
In the same PSG-verified study, higher sugar intake directly increased nighttime arousals — independently of fiber. Refined carb–heavy days fragment sleep even when total sleep time is unchanged.
Mechanism. Overnight glucose swings trigger sympathetic arousal; insulin/cortisol counter-regulation produces mid-night awakenings.
What to do. Minimize added sugar, especially after dinner
Caffeine
S
+12 min WASO
Read more ↓
Collapse ↑
The most robust evidence for a sleep-maintenance disruptor. Pooled across 24 studies, caffeine added roughly 12 minutes of time awake after sleep onset — on top of lengthening sleep latency. Slow metabolizers and late-day intake see larger effects.
Mechanism. Adenosine receptor antagonism blocks the homeostatic pressure that keeps you in consolidated sleep, producing lighter sleep and more spontaneous arousals.
What to do. Stop ≥8 hours before bed; slow metabolizers may need 10+ hours
Gardiner et al. 2023 meta-analysis
Alcohol
S
↑ fragmentation
Read more ↓
Collapse ↑
Alcohol may help you fall asleep faster at high doses, but it wrecks the second half of the night. As it metabolizes, sleep breaks apart — more awakenings, lower sleep efficiency, and lighter sleep. The effect scales with dose.
Mechanism. Initial GABA-A sedation is followed by rebound glutamate activity and disrupted REM as alcohol clears, producing mid-night arousals and shallower sleep.
What to do. Avoid within 3+ hours of bed; lower the dose or skip entirely
Late Eating (<1 hr pre-bed)
M
2–2.6× WASO odds
Read more ↓
Collapse ↑
Eating in the hour before bed more than doubled the odds of prolonged wake time after sleep onset. Late meals delay core temperature drop and raise the risk of reflux-driven awakenings.
Mechanism. Active digestion elevates core body temperature and sympathetic activity; reflux and glucose swings drive mid-night arousal.
What to do. Finish eating 2–3 hours before bed
Supplements
6
Helps you stay asleep
3
Ashwagandha (600 mg/day)
S
SMD −0.39 for WASO
Read more ↓
Collapse ↑
The strongest supplement-specific evidence for staying asleep. Pooled across 3 RCTs with 281 participants, ashwagandha produced a standardized mean difference of −0.39 for WASO — meaningfully less nighttime waking. 600 mg/day of standardized extract shows the largest effect.
Mechanism. Withanolides reduce cortisol and overnight sympathetic tone; GABAergic activity dampens the arousals that fragment sleep.
What to do. 600 mg/day standardized extract, split AM/PM or taken evening
Cheah et al. 2021 meta-analysis
View Ashwagandha Extract on Amazon
Glycine (3 g)
M
↓ WASO, faster SWS
Read more ↓
Collapse ↑
A small but polysomnography-verified study: 3 g of glycine before bed reduced nighttime waking and sped entry into slow-wave sleep. Small sample, but the mechanism is clean and the objective measurement is solid.
Mechanism. Peripheral vasodilation drops core body temperature (a deep-sleep signal); NMDA modulation reduces cortical arousal.
What to do. 3 g, 30–60 min before bed
Yamadera et al. 2007 PSG study
View Glycine Powder on Amazon
Magnesium (500 mg)
L
Positive for sleep efficiency
Read more ↓
Collapse ↑
Magnesium improved overall sleep efficiency in older adults with insomnia (P=0.03), but WASO itself was not directly measured. Early-morning awakening was only marginally better (P=0.08). Best evidence is in elderly people with low dietary magnesium.
Mechanism. NMDA receptor antagonism and GABA-A potentiation reduce cortical arousal; supports melatonin rhythm.
What to do. 200–500 mg elemental magnesium (glycinate preferred)
View Magnesium Glycinate on Amazon
Mixed or no clear effect
3
Melatonin (Immediate-Release)
S
No WASO effect
Read more ↓
Collapse ↑
The form of melatonin most people buy does not help you stay asleep. A 2022 meta-analysis in Neuropsychopharmacology found no significant WASO benefit for immediate-release melatonin. It shortens sleep onset and shifts circadian timing — but it won't keep you asleep.
Mechanism. Short half-life (~45 min) means exogenous melatonin is largely cleared before the second half of the night, so it cannot suppress overnight arousals.
What to do. Use for sleep onset or circadian shift, not maintenance
L-Theanine (200–450 mg)
L
Mixed WASO results
Read more ↓
Collapse ↑
L-theanine shows subjective relaxation benefits and some sleep-maintenance signal at 200–450 mg/day, but WASO results are inconsistent when it is isolated from combination products. Promising, not yet proven for staying asleep.
Mechanism. Increases alpha brain waves and GABA/glutamate balance; reduces cortisol and sympathetic tone without sedation.
What to do. 200–450 mg, 30–60 min before bed
View L-Theanine 200mg on Amazon
Valerian Root
W
No objective WASO benefit
Read more ↓
Collapse ↑
Despite widespread use, valerian does not consistently improve objective WASO. Subjective sleep ratings improve, but polysomnography and actigraphy do not confirm it. The perceived benefit may be placebo or from combination formulations.
Mechanism. Weak GABA-A modulation and adenosine receptor binding; clinical signal inconsistent across doses and preparations.
What to do. Not recommended as first-line for WASO
Shinjyo et al. 2020 meta-analysis
Exercise & Movement
5
Helps you stay asleep
4
Moderate Aerobic Exercise
S
−10 min WASO
Read more ↓
Collapse ↑
The strongest exercise evidence for sleep maintenance. A 2024 meta-analysis of RCTs in insomnia patients found regular moderate aerobic exercise cut WASO by about 10 minutes (MD = −10.16, p < .001). Reliable, well-tolerated, and works alongside other interventions.
Mechanism. Raises daytime energy expenditure, deepens homeostatic sleep pressure, lowers cortisol, and strengthens circadian amplitude.
What to do. 150+ min/week moderate intensity, consistent schedule
Riedel et al. 2024 meta-analysis
Resistance Training
M
↓ disturbance, ↑ efficiency
Read more ↓
Collapse ↑
Strength training improved mid-sleep disturbance and sleep efficiency across 13 studies. WASO was not pooled specifically, but individual RCTs showed reductions. Works on its own and stacks well with cardio.
Mechanism. Elevated growth hormone and muscle-recovery demands deepen slow-wave sleep; reduced anxiety and stable glucose lower overnight arousals.
What to do. 2–3 sessions per week, progressive overload
Yoga
L
−56 min WASO, likely inflated
Read more ↓
Collapse ↑
Yoga showed the largest raw WASO reduction in the 2025 network meta-analysis — about 56 minutes in insomnia patients. Flagged as low-certainty because of small samples and heterogeneity, so the effect size is likely inflated. Still worth trying given the low downside.
Mechanism. Pranayama breathing reduces sympathetic tone; gentle physical load supports circadian amplitude; mindfulness reduces rumination-driven arousals.
What to do. Regular practice; 3+ sessions per week
Bu et al. 2025 network meta-analysis
Moderate Evening Exercise
M
↓ WASO
Read more ↓
Collapse ↑
Moderate-intensity evening exercise reduced WASO across a broad review — contrary to the old 'never train at night' advice. Only vigorous, close-to-bedtime sessions carry risk; ordinary evening workouts help you stay asleep.
Mechanism. Moderate post-exercise cooling and parasympathetic rebound support the overnight core-temperature drop and reduced sympathetic tone needed for consolidated sleep.
What to do. Moderate intensity, finish 1.5+ hrs before bed
Wakes you up
1
Vigorous Exercise ≤1 hr Pre-Bed
M
+21.9 min WASO
Read more ↓
Collapse ↑
Vigorous training that ends within an hour of bedtime measurably fragments sleep — particularly when intensity exceeds your usual level (b = +21.9 min WASO, p = 0.044). Any exercise during the day is fine; just keep the hardest effort away from bedtime.
Mechanism. Sympathetic activation, catecholamine surge, and elevated core temperature oppose the physiological drop needed to stay in consolidated sleep.
What to do. Avoid high-intensity exercise in the hour before bed
Stutz et al. 2019 meta-analysis
Environment & Hygiene
5
Helps you stay asleep
2
Bedroom Temp (20–25°C)
S
Positive at optimal range
Read more ↓
Collapse ↑
Both too-hot and too-cold bedrooms measurably increase WASO. The 20–25°C (68–77°F) range is consistently supported; most sleep research points to the cooler end. Individual preference varies.
Mechanism. Ambient temperature outside the thermoneutral zone prevents the core-to-skin heat transfer that maintains deep sleep, producing mid-night arousals.
What to do. Aim for 18–22°C (65–72°F); layer bedding to fine-tune
Akiyama 2021 thermal environment study
Mattress (Medium-Firm)
L
Most consistent WASO
Read more ↓
Collapse ↑
A small polysomnography study found a medium-firm mattress produced the most stable sleep and lowest WASO across three firmness levels. Very small sample, but the direction is consistent with broader ergonomic data.
Mechanism. Appropriate spinal support reduces micro-movements and pressure-point arousals that fragment sleep across the night.
What to do. Medium-firm mattress; replace every 7–10 years
View Medium-Firm Mattress on Amazon
Wakes you up
3
Light at Night (even dim)
S
↑ WASO
Read more ↓
Collapse ↑
Even dim light during sleep — roughly a nightlight at 5–10 lux — significantly increased WASO and shallow REM on polysomnography. You don't have to be looking at a screen; ambient bedroom light is enough to fragment sleep.
Mechanism. Melanopsin-containing retinal ganglion cells detect light through the eyelids, suppressing melatonin and raising cortical arousal.
What to do. Bedroom as dark as possible; cover electronics, use blackout
View Sleep Mask on Amazon
Noise (>50 dBA)
S
+30 min WASO
Read more ↓
Collapse ↑
The most comprehensive environmental sleep review to date. Nighttime noise above 50 dBA added roughly 30 minutes of WASO in the reviewed field studies. Traffic, aircraft, and intermittent neighborhood noise all show dose-response effects.
Mechanism. Auditory cortex activation and autonomic arousal interrupt NREM stages; even sub-conscious arousals fragment sleep architecture.
What to do. Keep bedroom <30 dB; use masking (white/pink noise) or earplugs
View Earplugs on Amazon
CO₂ >1000 ppm (Poor Ventilation)
M
+5 min wake
Read more ↓
Collapse ↑
A well-designed balanced crossover study found even moderate CO₂ buildup (~1,000 ppm) added measurable wake time during the night. A stuffy, poorly ventilated bedroom is a real and often-overlooked WASO driver.
Mechanism. Elevated CO₂ increases ventilatory drive, sympathetic tone, and micro-arousals; reduced O₂ saturation compounds the effect.
What to do. Crack a window or use mechanical ventilation; aim <800 ppm
View CO₂ Monitor on Amazon
Demographics & Physiology
9
Wakes you up
8
Aging (30–60+)
S
+10 min WASO/decade
Read more ↓
Collapse ↑
The definitive reference on normal sleep architecture. WASO increases roughly 10 minutes per decade between age 30 and 60, then plateaus. Expected, not pathological — but it compounds with other age-related changes like lighter sleep and more frequent bathroom trips.
Mechanism. Reduced SCN amplitude, blunted nocturnal melatonin, and thinner cortical sleep architecture all increase spontaneous arousals.
What to do. Non-modifiable; offset with morning light, exercise, sleep hygiene
Ohayon et al. 2004 meta-analysis
Menopausal Hot Flashes
S
69% hot flashes → wake
Read more ↓
Collapse ↑
A controlled GnRH-agonist model with polysomnography found 69% of women developed vasomotor symptoms, and each additional nighttime hot flash increased WASO by 62% (P=0.007). Hot flashes accounted for about 27% of total WASO. HRT, cooling strategies, and CBT-I all help.
Mechanism. Vasomotor episodes produce abrupt heat surges that directly trigger awakening; autonomic destabilization keeps sleep light between episodes.
What to do. HRT, cooling bedroom, moisture-wicking bedding; CBT-I adjunct
Obesity (BMI ≥30)
S
↑ WASO
Read more ↓
Collapse ↑
A large PSG-based cohort found WASO was independently associated with obesity after full adjustment (OR 1.003 per minute, P=0.007). Cross-sectional — so directionality is uncertain — but the link is well-established and bi-directional with sleep apnea.
Mechanism. Upper-airway loading (even without OSA), increased inflammation, and altered thermoregulation all raise overnight arousals.
What to do. Weight management; screen for OSA if BMI ≥30
Shift Work
M
↑ WASO, ↓ efficiency
Read more ↓
Collapse ↑
Shift workers — especially those with diagnosable shift work sleep disorder — show more fragmented daytime sleep, higher WASO, and lower efficiency. The mismatch between sleep time and circadian phase is the core issue.
Mechanism. Daytime sleep attempts fight the circadian alerting signal; light, noise, and social obligations interrupt the rest window.
What to do. Strategic light, blackout sleep environment, timed melatonin, naps
Wickwire et al. 2017 Chest review
Nocturia (≥2 episodes/night)
S
+34 min WASO
Read more ↓
Collapse ↑
One of the most impactful real-world WASO drivers and commonly overlooked. WASO climbed from 55.5 min (0 episodes) to 89.8 min (3–4 episodes) — a 34-minute swing. Nocturia frequency explained 6% additional variance in WASO beyond all other factors.
Mechanism. Each bathroom trip is a full arousal plus ambient light exposure plus cold sheets on return — compounding sleep fragmentation.
What to do. Limit evening fluids; rule out BPH, overactive bladder, OSA-driven ANP
Obstructive Sleep Apnea
S
↑ WASO, ↑ arousals with severity
Read more ↓
Collapse ↑
Among the most well-established causes of sleep fragmentation in medicine. Every obstructive breathing event triggers an arousal — by definition. WASO and arousal index scale directly with apnea-hypopnea index. Diagnosis and treatment (CPAP, oral appliance) produce large WASO reductions.
Mechanism. Repeated airway collapse triggers cortical arousal to restore airway patency; each event fragments NREM and prevents consolidated sleep.
What to do. Screen with home sleep test if suspected; treat with CPAP or oral appliance
Chronic Pain
S
Large effect
Read more ↓
Collapse ↑
PSG-measured WASO roughly doubles in people with chronic pain versus healthy controls across 37 studies. Pain directly interrupts sleep, and the resulting fatigue lowers pain tolerance the next day — a vicious cycle that CBT-I and pain-focused therapy can both break.
Mechanism. Nociceptive input continues through sleep, producing repeated arousals; central sensitization amplifies even minor stimuli into full awakenings.
What to do. Treat underlying pain; CBT-I improves both pain and sleep outcomes
Mathias et al. 2018 meta-analysis
Psychological Stress
M
↑ WASO via cortisol
Read more ↓
Collapse ↑
The foundational paper for the 'hyperarousal' model of sleep-maintenance insomnia. Chronic insomnia patients showed elevated 24-hour cortisol — particularly pre-sleep and during the first half of the night — directly fragmenting sleep. Stress hormones are a real, measurable WASO driver.
Mechanism. HPA axis activation elevates cortisol and sympathetic tone, which lowers arousal threshold and produces spontaneous mid-night awakenings.
What to do. CBT-I, mindfulness, cognitive restructuring; address chronic stressors
Mixed or no clear effect
1
Female Sex (Subjective–Objective Paradox)
S
More complaints, better PSG
Read more ↓
Collapse ↑
A well-documented paradox: women report more sleep complaints across every age group, yet show objectively better sleep continuity on polysomnography than men. Hormonal cycles, perimenopause, and insomnia prevalence likely explain the subjective side.
Mechanism. Hormonal fluctuations (menstrual, perimenopausal) drive perceived sleep disruption; baseline sleep architecture remains objectively stronger than age-matched men.
What to do. Non-modifiable; address specific drivers (hormonal, hot flashes, anxiety)
Ohayon et al. 2004 meta-analysis
Six headlines from the data
If you only remember six things.
Biggest hurter
+34 min
Nocturia (≥2 trips)
SOF study, n=1,520 — WASO climbs from 55.5 → 89.8 min as trips go 0 → 3–4.
Biggest helper
−17 min
Tart cherry juice
Pigeon 2010 RCT crossover, n=15 insomnia adults. Needs replication, but the signal is clean.
Hidden environment
+30 min
Noise over 50 dBA
WHO review of 74 studies. Even intermittent neighborhood noise shows dose-response effects.
Reliable daily win
−10 min
Moderate aerobic exercise
Riedel 2024 meta-analysis of insomnia RCTs. MD = −10.16 min WASO, p < .001.
Myth, busted
±0 min
Melatonin (standard)
Menczel Schrire 2022 meta-analysis — no significant WASO effect. Use for onset, not maintenance.
Quickest fix
Tonight
Kill dim bedroom light
Cho 2016 PSG — even 5–10 lux (nightlight-level) measurably raises WASO. Blackout the bedroom.
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Nutrition · 28 sources
Open
Sources
All data sourced from peer-reviewed studies and meta-analyses.
Nutrition & Substances
St-Onge et al. 2016 — Fiber, saturated fat & sleep arousals
J Clin Sleep Med
Nutrition & Substances
Gardiner et al. 2023 — Caffeine & WASO meta-analysis
24 studies
Nutrition & Substances
Spadola et al. 2019 — Evening alcohol & sleep fragmentation
Jackson Heart Study, n=785
Nutrition & Substances
Crispim et al. 2022 — Bedtime eating & WASO
British J Nutrition
Nutrition & Substances
Pigeon et al. 2010 — Tart cherry juice & WASO pilot RCT
journals.sagepub.com
Supplements
Menczel Schrire et al. 2022 — Melatonergic agents meta-analysis
Neuropsychopharmacology
Supplements
Cheah et al. 2021 — Ashwagandha & sleep meta-analysis
5 RCTs, n=400
Supplements
Yamadera et al. 2007 — Glycine 3 g & PSG sleep-quality study
onlinelibrary.wiley.com
Supplements
Abbasi et al. 2012 — Magnesium & insomnia in elderly RCT
pubmed.ncbi.nlm.nih.gov
Supplements
2025 Systematic Review — L-theanine & sleep dietary trials
Nutritional Neuroscience
Supplements
Shinjyo et al. 2020 — Valerian root & sleep meta-analysis
60 studies
Exercise & Movement
Riedel et al. 2024 — Exercise & insomnia meta-analysis
−10.16 min WASO
Exercise & Movement
Kovacevic et al. 2018 — Resistance exercise & sleep review
13 studies
Exercise & Movement
Bu et al. 2025 — Exercise interventions in insomnia network meta-analysis
22 RCTs
Exercise & Movement
Dolezal et al. 2017 — Sleep & exercise interrelationship review
onlinelibrary.wiley.com
Exercise & Movement
Stutz et al. 2019 — Evening exercise & sleep meta-analysis
Sports Med
Environment & Sleep Hygiene
Akiyama 2021 — Thermal environment & sleep quality in actual bedrooms
onlinelibrary.wiley.com
Environment & Sleep Hygiene
Cho et al. 2016 — Dim light at night & REM/awakenings
Chronobiology Int
Environment & Sleep Hygiene
Basner et al. 2018 — WHO environmental noise & sleep review
74 studies
Environment & Sleep Hygiene
Kang et al. 2024 — CO₂ concentration & sleep
Building & Environment
Environment & Sleep Hygiene
Hu et al. 2025 — Mattress firmness & sleep architecture
PSG
Demographics & Physiology
Ohayon et al. 2004 — Normative sleep parameters meta-analysis
65 studies
Demographics & Physiology
Joffe et al. 2013 — GnRH model: hot flashes interrupt objective sleep
pubmed.ncbi.nlm.nih.gov
Demographics & Physiology
Zhao et al. 2021 — Sleep fragmentation & obesity
Sleep Heart Health Study, n=5,723
Demographics & Physiology
Wickwire et al. 2017 — Shift work & shift work sleep disorder
Chest
Demographics & Physiology
Fung et al. 2017 — Nocturia & sleep quality in older women
SOF, n=1,520
Demographics & Physiology
Patel 2019 — Obstructive sleep apnea review
Annals Internal Medicine
Demographics & Physiology
Mathias et al. 2018 — Sleep disturbances in chronic pain meta-analysis
37 studies
Demographics & Physiology
Vgontzas et al. 2001 — Chronic insomnia & HPA axis activation
pubmed.ncbi.nlm.nih.gov
Show all 29 sources
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This content is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider before starting any supplement, exercise program, or lifestyle change.
Data sourced from peer-reviewed studies and meta-analyses. Last updated April 2026.
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Sleep
How to Stay Asleep All Night: 31 Factors Ranked by Evidence (2026)
Forty-plus studies ranked by what actually moves WASO. Some confirm what you expect; immediate-release melatonin does not.
8 min read
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Sleep
How to Fall Asleep Faster: 33 Factors Ranked by Evidence (2026)
Thirty-three factors that change sleep latency, from caffeine and melatonin to warm baths and bedroom temperature, each graded.
10 min read
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App Updates
Which Foods Affect Your Sleep & HRV? How to Find Out
Caffeine, alcohol and late heavy meals are the usual suspects, but the foods that move your numbers are personal. How to find yours.
7 min read
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